电沉积块体纳米晶Ni的压缩力学行为及微观结构演化研究
|
摘要
上世纪八十年代末，纳米金属材料研究的先驱Gleiter教授在其名为“Nanocrystalline materials”的里程碑式的论文中指出，若能够将金属材料的晶粒尺寸减小到纳米尺度（10-9m）会使材料的各种性能得到极大的提高。这一开创性论断的提出使金属材料的研究进入了一个崭新的阶段。在过去的二十余年中，纳米晶金属材料一直是材料科学领域研究的一个热点。这主要是由于和传统的粗晶金属材料相比，纳米晶金属材料具有更高的屈服强度和断裂强度，更好的耐摩擦/磨损性能以及低温/高应变速率超塑性等优异的力学性能，从而在诸多领域具有广泛的潜在应用前景。不仅如此，纳米晶金属材料还为研究材料在微纳尺度上的变型机制提供了的理想平台。材料科学界对纳米晶金属材料的制备、微观结构、力学性能及变形机制等已开展了大量的卓有成效的研究工作。尽管如此，仍有一些根本性的问题尚未得到充分地研究和解决。首先，由于材料制备工艺的限制，以往多采用薄片状试样通过拉伸试验对纳米晶金属材料的力学行为进行研究，试验中获得的应变量极为有限。这极大地限制了对纳米晶金属材料在大塑性变形过程中结构演化和力学行为的研究。其次，对纳米晶金属材料的断裂行为和机制目前尚无清楚的认识且相关的研究结果还极为有限。特别是尽管计算机模拟和实验观察均表明微孔聚集机制是纳米晶金属材料断裂的主要机制之一，但还不清楚纳米晶尺寸和界面效应以及杂质元素的存在对微孔的形成及演化究竟有着怎样的影响。
基于以上原因，本博士论文采用块体纳米晶Ni作为模型材料，综合利用MTS-810综合力学性能测试系统、X射线衍射仪(XRD)、透射电子显微镜(TEM)、配有二次电子背散射探头的扫描电子显微镜(SEM-EBSD)对纳米晶Ni在大塑性压缩变形过程中的微观结构演化、力学行为和断裂机制等进行了系统的研究。还结合实验观察结果，利用大规模三维计算机分子动力学模拟对压缩过程中孔洞的形成和演化进行了分析。
实验中使用的纳米晶Ni采用电沉积方法制备。我们在传统Watts镀液基础上通过添加糖精、1,4-丁炔二醇及十二烷基硫酸钠等添加剂开发出一种基于直流电沉积方法制备大块体纳米晶Ni的新工艺。采用此工艺制备出的纳米晶Ni纯度达到99.5%(质量分数)，且无有明显的织构，晶粒细小，晶体学取向均匀。基于对TEM观察结果的统计分析和XRD分析得出纳米晶Ni的平均晶粒尺寸为20±6nm。镀层厚度达到了7~8mm，为进行大块纳米晶金属压缩变形研究提供了必要的试样。
室温单向准静态压缩实验表明在10-5s-1至10-5s-1的应变速率范围内，纳米晶Ni都表现较高的强度(最高压缩强度为2.3~2.5GPa)和极佳的塑性(压缩应变量达到0.3~0.36)。变速率敏感指数和激活体积的计算结果表明纳米晶Ni的塑性变形是由位错机制主导的。而对变形后试样微观结构的观察进一步验证了这一点。TEM和高分辨TEM(HRTEM)观察发现了显著的晶内位错塞积和大量的部分位错协调机制开动的痕迹(堆垛层错和孪晶)，而孪晶界与位错的相互作用是实现晶内位错塞积的主要原因。这是首次在室温和单向加载条件下变形的纳米晶金属中观察到显著的晶内位错塞积现象。在变形过程中孪晶界/晶界与位错的相互作用使这些界面由变形前的平衡态转变为非平衡态。而非平衡晶界/孪晶界的形成，一方面促进了部分位错从晶界/孪晶界处发射，另一方面也使起主导作用的微观热激活过程发生了改变，从而导致在变形的不同阶段纳米晶Ni的应变速率敏感指数和激活体积也相应地发生了变化。
在经过大塑性压缩变形(ε=~0.36)后的纳米晶Ni中观察到了非晶态结构的存在。非晶态结构主要集中分布于局部塑性变形较大的区域内，如裂纹和孔洞周围。HRTEM观察及能量散射谱与能量损失谱分析表明非晶态结构的形成是变形过程中发生了固态非晶化转变的结果。这是首次在面心立方结构的单质纯金属中观察到固态非晶化转变的发生。纳米晶金属材料中细小的晶粒和大量的晶界使其本身在未变形前就具有较高的自由能，而塑性变形过程中晶界和位错等变形缺陷的引入使晶态结构的自由能进一步升高直至最终高于相应的非晶态结构的自由能，导致非晶化转变的发生。两种状态间的自由能差则成为非晶态转变发生的驱动力。非晶态结构的形成很有可能是纳米晶金属材料经过大塑性变形后一种本征的结构特征。
TEM和SEM观察发现大塑性压缩变形(ε=~0.3)后纳米晶Ni中出现了大量的孔洞。孔洞的尺寸从几纳米到几百纳米不等。HRTEM观察表明这些孔洞主要在晶界和三叉晶界处萌生。计算机分子动力学模拟表明孔洞的形成主要受局部应力/应变状态和杂质元素的影响。局部拉应力状态和平面应变状态会促进孔洞的形核和长大。而局部压应力状态则抑制孔洞的形成。氢作为杂质元素存在时对孔洞的形成有“催化”作用。HRTEM观察和计算机模拟都表明孔洞的长大与位错在孔洞表面的发射和吸收密切相关，但氢原子的存在使孔洞长大在一定程度上可通过空位的扩散和聚集实现。孔洞的产生与纳米晶材料中特殊的界面和尺寸效应有关。纳米晶Ni塑性变形过程中严重的应变不协调导致的应力集中，位错与晶界的相互作用及杂质元素的存在可能是导致孔洞产生的主要原因。
纳米晶Ni在压缩变形过程中的断裂行为表现出一定程度的应变依赖。当变形量较小时(ε=~0.3)，试样仅沿着一个主断裂面断裂成为两个部分。TEM和SEM观察发现纳米晶Ni的断裂方式为微孔聚集型断裂，沿晶脆性断裂与滑移剪切断裂共存的混合型断裂。多种断裂机制共同作用使断裂表面呈现出多种不同的形貌。而当变形量较大时(ε=~1.2)，试样以破碎的方式失效，在压缩载荷的作用下碎裂成大小、形状各异的碎块。HRTEM观察和微区XRD (GADDS)分析发现变形过程中发生的局部固态非晶化对材料的断裂产生了显著的影响。非晶结构的形成为裂纹提供了更多的“形核点”和“快速扩展通道”，促进了裂纹的大量形成和快速传播并最终导致发生粉碎性断裂的发生。
In the late-1980s, Prof. Gleiter made the visionary argument that metals and alloys, ifmade nanocrystalline (NC), would have a number of appealing mechanical characteristics ofpotential significance for structural applications. This provocative thought has opened up awhole new area of the research of metallic materials. The past two decades have witnessed asurge in research effects through the whole materials research community addressed uponNC metals and alloys. This is mainly because NC metals and alloys are highly desirablenot only for technological applications exploiting their compelling mechanical properties,such as ultra-high yield and fracture strength, superior wear resistance and low-temperaturesuperplastic formability; but also for scientific research as they offer new opportunities toinvestigate deformation behaviors at an extremely fine microstructural scale. Despite someuseful from both experimental and computational investigations, some critical issues remaincontroversial and need to be further explored. First of all, due to the synthesis limitations,most of the mechanical test on NC metals so far carried are limited to tensile test with verythin samples. The early necking and subsequent limited ductility revealed by NC metals intensile tests severely restrict the experimentally accessible parameter space. As a result, theeffect of large deformation on NC metals has not been explored to develop a lucid under-standing. More than that, in comparison with the inspiring progress that has been made inboth achieving extraordinary mechanical properties and uncovering unique deformation be-haviors in nano-materials, their fracture behaviors are only beginning to be understood. Inparticular, such understanding should inevitably include comprehensive knowledge of initia-tion, growth and coalescence of voids, which dominates the ductile fracture ofcoarse-grained (CG) metals and has been proven to also play a critical role in controlling thefailure of NC metals and alloys. Nevertheless, how such voids initiate and evolve in NCmetals seems a problem being laid dormant and few experimental studies have been ad-dressed upon this issue.
In this work, to address upon these fundamental issues, we chose bulk NC Ni asmodel materials and systematically investigate their deformation behavior and microstruc-ture evolution during large-strain compression. The morphologies and microstructures of the NC Ni samples before and after deformation were extensively studied by X-ray diffractmeter(XRD), transmission electron microscope (TEM) and high-resolution TEM (HRTEM), scan-ning electron microscope (SEM) and electron backscattered diffraction-transmission Kiku-chi diffraction technology (EBSD-TKD) etc.
A surfactant-assistant direct-current electrodeposition technique was proposed and ex-ploited to synthesize bulk NC Ni used in the present study. By reasonably controlling thecontent of additives and current density, high-purity, fully-dense bulk NC Ni sheets withmaximum dimension of up to7~8mm in thickness were successfully fabricated. The NC Niconsisted of roughly equiaxed grains with random orientations and the average grain sizewas estimated to be20±6nm. Most of the nano-grains were found to be separated byhigh-angle GBs whereas no GB phases (e.g. amorphous layers) were detected. A high purityof the as-deposited NC Ni (99.92%, weight percent) was revealed by the chemical analysis.Room-temperature uni-axial quasi-static compression tests were carried out on a MTS-810mechanical testing system in both unconfined and confined manners to introduced largeplastic strain in the range of0.36~1.2, which enables systematic exploration of the deforma-tion mechanisms and microstructure evolution over a relatively wide range of strain.
Over the strain rate range from10-5s-1to10-1s-1(but excluding10-3s-1), the NC Ni exhi-bited remarkably enhanced plasticity: the compressive strain to failure reaches~0.3at allstrain rates, far beyond that can be obtained in tension. Also, the NC Ni exhibited ultra-highstrength with the maximum compressive strength ranging from2197MPa to2490MPa. Wedemonstrated, for the first time, significant intra-grain dislocation accumulation, as well aspropensity of deformation twinning and faulting in a NC Ni deformed at room temperatureand under conventional uniaxial loading. The equilibrium to non-equilibrium transforma-tions of GBs and TBs, induced by large plastic deformation, were also observed. Such trans-formations on one hand promote PDMPs; on the other hand, causes switch of the dominantmicroscopic thermal-activated process at different stages of deformation, which was mani-fested as the varying activation volume and strain rate sensitivity index at the different stagesduring deformation.
We present experimental evidence of localized solid-state amorphization in bulk nano-crystalline nickel introduced by quasi-static compression at room temperature.High-resolution electron microscope observations illustrate that nano-scale amorphousstructures present at the regions where severe deformation occurred, e.g. along crack paths orsurrounding nano-voids. High densities of GBs and dislocations, both of which are intro- duced by localized heavy plastic deformation, contribute significantly to destabilizing thecrystalline structure and to driving the solid-state amorphization. Upon such a scenario, na-nocrystalline structures facilitate the c-a transformation both thermodynamically and kineti-cally. It is noteworthy that the grain-refinement-induced and disloca-tion-accumulation-induced amorphization operate concomitantly throughout the sample, butit is possible that, for a given region in the sample, only one of the two mechanisms domi-nates the c-a transformation, probably depending on the local stress state and strain condition.Amorphization might be the intrinsic structural feature in NC metals and alloys that weredeformed to large strains.
Extensive formation of nano-voids, which was primarily attributed to the severe plasticincompatibility in NC metals, was identified during large-strain compression of NC Ni. De-tailed postmortem TEM and HRTEM observations, together with MD simulation results,have drawn a conclusive picture concerning nano-void evolution in NC metals: the void in-itiation preferentially take place and TJs and GBs, and then dislocation emission and absorp-tion are responsible for the outward flux of matter, promoting their growth, until they coa-lescence into larger ones. The local stress/strain conditions were identified to significant in-fluence the nucleation and evolution of the nano-voids. Moreover, the impurities introducedduring electrodeposition, in particular the hydrogen, also play a crucial role in “catalyzing”the nucleation of the nano-voids. In such a case, vacancy diffusion may also be in part re-sponsible for the void expansion.
We provide compelling experimental evidence for a novel failure mode in NC Ni in-volving deformation-induced amorphization during large strain plastic deformation. Thefailure of the NC Ni was found to be somewhat strain-dependent. When deformation is rela-tively small (ε=0.3), the sample fractured into two parts by sliding one part relative to anoth-er along the plane inclined approximately45°relative to the compression axis. Signatures ofmicro-void coalescence fracture, intergranular fracture and shear-slipped fracture can beidentified during TEM and SEM investigations. But when large plastic deformation was im-posed (ε=1.2), the generation of large amount of relatively “weak” amorphous structuresprovide preferable sites for crack initiation and easy means for cleavage fracture, giving riseto the change in the fracture morphology and thereby fragmentation-type failure.
基于以上原因，本博士论文采用块体纳米晶Ni作为模型材料，综合利用MTS-810综合力学性能测试系统、X射线衍射仪(XRD)、透射电子显微镜(TEM)、配有二次电子背散射探头的扫描电子显微镜(SEM-EBSD)对纳米晶Ni在大塑性压缩变形过程中的微观结构演化、力学行为和断裂机制等进行了系统的研究。还结合实验观察结果，利用大规模三维计算机分子动力学模拟对压缩过程中孔洞的形成和演化进行了分析。
实验中使用的纳米晶Ni采用电沉积方法制备。我们在传统Watts镀液基础上通过添加糖精、1,4-丁炔二醇及十二烷基硫酸钠等添加剂开发出一种基于直流电沉积方法制备大块体纳米晶Ni的新工艺。采用此工艺制备出的纳米晶Ni纯度达到99.5%(质量分数)，且无有明显的织构，晶粒细小，晶体学取向均匀。基于对TEM观察结果的统计分析和XRD分析得出纳米晶Ni的平均晶粒尺寸为20±6nm。镀层厚度达到了7~8mm，为进行大块纳米晶金属压缩变形研究提供了必要的试样。
室温单向准静态压缩实验表明在10-5s-1至10-5s-1的应变速率范围内，纳米晶Ni都表现较高的强度(最高压缩强度为2.3~2.5GPa)和极佳的塑性(压缩应变量达到0.3~0.36)。变速率敏感指数和激活体积的计算结果表明纳米晶Ni的塑性变形是由位错机制主导的。而对变形后试样微观结构的观察进一步验证了这一点。TEM和高分辨TEM(HRTEM)观察发现了显著的晶内位错塞积和大量的部分位错协调机制开动的痕迹(堆垛层错和孪晶)，而孪晶界与位错的相互作用是实现晶内位错塞积的主要原因。这是首次在室温和单向加载条件下变形的纳米晶金属中观察到显著的晶内位错塞积现象。在变形过程中孪晶界/晶界与位错的相互作用使这些界面由变形前的平衡态转变为非平衡态。而非平衡晶界/孪晶界的形成，一方面促进了部分位错从晶界/孪晶界处发射，另一方面也使起主导作用的微观热激活过程发生了改变，从而导致在变形的不同阶段纳米晶Ni的应变速率敏感指数和激活体积也相应地发生了变化。
在经过大塑性压缩变形(ε=~0.36)后的纳米晶Ni中观察到了非晶态结构的存在。非晶态结构主要集中分布于局部塑性变形较大的区域内，如裂纹和孔洞周围。HRTEM观察及能量散射谱与能量损失谱分析表明非晶态结构的形成是变形过程中发生了固态非晶化转变的结果。这是首次在面心立方结构的单质纯金属中观察到固态非晶化转变的发生。纳米晶金属材料中细小的晶粒和大量的晶界使其本身在未变形前就具有较高的自由能，而塑性变形过程中晶界和位错等变形缺陷的引入使晶态结构的自由能进一步升高直至最终高于相应的非晶态结构的自由能，导致非晶化转变的发生。两种状态间的自由能差则成为非晶态转变发生的驱动力。非晶态结构的形成很有可能是纳米晶金属材料经过大塑性变形后一种本征的结构特征。
TEM和SEM观察发现大塑性压缩变形(ε=~0.3)后纳米晶Ni中出现了大量的孔洞。孔洞的尺寸从几纳米到几百纳米不等。HRTEM观察表明这些孔洞主要在晶界和三叉晶界处萌生。计算机分子动力学模拟表明孔洞的形成主要受局部应力/应变状态和杂质元素的影响。局部拉应力状态和平面应变状态会促进孔洞的形核和长大。而局部压应力状态则抑制孔洞的形成。氢作为杂质元素存在时对孔洞的形成有“催化”作用。HRTEM观察和计算机模拟都表明孔洞的长大与位错在孔洞表面的发射和吸收密切相关，但氢原子的存在使孔洞长大在一定程度上可通过空位的扩散和聚集实现。孔洞的产生与纳米晶材料中特殊的界面和尺寸效应有关。纳米晶Ni塑性变形过程中严重的应变不协调导致的应力集中，位错与晶界的相互作用及杂质元素的存在可能是导致孔洞产生的主要原因。
纳米晶Ni在压缩变形过程中的断裂行为表现出一定程度的应变依赖。当变形量较小时(ε=~0.3)，试样仅沿着一个主断裂面断裂成为两个部分。TEM和SEM观察发现纳米晶Ni的断裂方式为微孔聚集型断裂，沿晶脆性断裂与滑移剪切断裂共存的混合型断裂。多种断裂机制共同作用使断裂表面呈现出多种不同的形貌。而当变形量较大时(ε=~1.2)，试样以破碎的方式失效，在压缩载荷的作用下碎裂成大小、形状各异的碎块。HRTEM观察和微区XRD (GADDS)分析发现变形过程中发生的局部固态非晶化对材料的断裂产生了显著的影响。非晶结构的形成为裂纹提供了更多的“形核点”和“快速扩展通道”，促进了裂纹的大量形成和快速传播并最终导致发生粉碎性断裂的发生。
In the late-1980s, Prof. Gleiter made the visionary argument that metals and alloys, ifmade nanocrystalline (NC), would have a number of appealing mechanical characteristics ofpotential significance for structural applications. This provocative thought has opened up awhole new area of the research of metallic materials. The past two decades have witnessed asurge in research effects through the whole materials research community addressed uponNC metals and alloys. This is mainly because NC metals and alloys are highly desirablenot only for technological applications exploiting their compelling mechanical properties,such as ultra-high yield and fracture strength, superior wear resistance and low-temperaturesuperplastic formability; but also for scientific research as they offer new opportunities toinvestigate deformation behaviors at an extremely fine microstructural scale. Despite someuseful from both experimental and computational investigations, some critical issues remaincontroversial and need to be further explored. First of all, due to the synthesis limitations,most of the mechanical test on NC metals so far carried are limited to tensile test with verythin samples. The early necking and subsequent limited ductility revealed by NC metals intensile tests severely restrict the experimentally accessible parameter space. As a result, theeffect of large deformation on NC metals has not been explored to develop a lucid under-standing. More than that, in comparison with the inspiring progress that has been made inboth achieving extraordinary mechanical properties and uncovering unique deformation be-haviors in nano-materials, their fracture behaviors are only beginning to be understood. Inparticular, such understanding should inevitably include comprehensive knowledge of initia-tion, growth and coalescence of voids, which dominates the ductile fracture ofcoarse-grained (CG) metals and has been proven to also play a critical role in controlling thefailure of NC metals and alloys. Nevertheless, how such voids initiate and evolve in NCmetals seems a problem being laid dormant and few experimental studies have been ad-dressed upon this issue.
In this work, to address upon these fundamental issues, we chose bulk NC Ni asmodel materials and systematically investigate their deformation behavior and microstruc-ture evolution during large-strain compression. The morphologies and microstructures of the NC Ni samples before and after deformation were extensively studied by X-ray diffractmeter(XRD), transmission electron microscope (TEM) and high-resolution TEM (HRTEM), scan-ning electron microscope (SEM) and electron backscattered diffraction-transmission Kiku-chi diffraction technology (EBSD-TKD) etc.
A surfactant-assistant direct-current electrodeposition technique was proposed and ex-ploited to synthesize bulk NC Ni used in the present study. By reasonably controlling thecontent of additives and current density, high-purity, fully-dense bulk NC Ni sheets withmaximum dimension of up to7~8mm in thickness were successfully fabricated. The NC Niconsisted of roughly equiaxed grains with random orientations and the average grain sizewas estimated to be20±6nm. Most of the nano-grains were found to be separated byhigh-angle GBs whereas no GB phases (e.g. amorphous layers) were detected. A high purityof the as-deposited NC Ni (99.92%, weight percent) was revealed by the chemical analysis.Room-temperature uni-axial quasi-static compression tests were carried out on a MTS-810mechanical testing system in both unconfined and confined manners to introduced largeplastic strain in the range of0.36~1.2, which enables systematic exploration of the deforma-tion mechanisms and microstructure evolution over a relatively wide range of strain.
Over the strain rate range from10-5s-1to10-1s-1(but excluding10-3s-1), the NC Ni exhi-bited remarkably enhanced plasticity: the compressive strain to failure reaches~0.3at allstrain rates, far beyond that can be obtained in tension. Also, the NC Ni exhibited ultra-highstrength with the maximum compressive strength ranging from2197MPa to2490MPa. Wedemonstrated, for the first time, significant intra-grain dislocation accumulation, as well aspropensity of deformation twinning and faulting in a NC Ni deformed at room temperatureand under conventional uniaxial loading. The equilibrium to non-equilibrium transforma-tions of GBs and TBs, induced by large plastic deformation, were also observed. Such trans-formations on one hand promote PDMPs; on the other hand, causes switch of the dominantmicroscopic thermal-activated process at different stages of deformation, which was mani-fested as the varying activation volume and strain rate sensitivity index at the different stagesduring deformation.
We present experimental evidence of localized solid-state amorphization in bulk nano-crystalline nickel introduced by quasi-static compression at room temperature.High-resolution electron microscope observations illustrate that nano-scale amorphousstructures present at the regions where severe deformation occurred, e.g. along crack paths orsurrounding nano-voids. High densities of GBs and dislocations, both of which are intro- duced by localized heavy plastic deformation, contribute significantly to destabilizing thecrystalline structure and to driving the solid-state amorphization. Upon such a scenario, na-nocrystalline structures facilitate the c-a transformation both thermodynamically and kineti-cally. It is noteworthy that the grain-refinement-induced and disloca-tion-accumulation-induced amorphization operate concomitantly throughout the sample, butit is possible that, for a given region in the sample, only one of the two mechanisms domi-nates the c-a transformation, probably depending on the local stress state and strain condition.Amorphization might be the intrinsic structural feature in NC metals and alloys that weredeformed to large strains.
Extensive formation of nano-voids, which was primarily attributed to the severe plasticincompatibility in NC metals, was identified during large-strain compression of NC Ni. De-tailed postmortem TEM and HRTEM observations, together with MD simulation results,have drawn a conclusive picture concerning nano-void evolution in NC metals: the void in-itiation preferentially take place and TJs and GBs, and then dislocation emission and absorp-tion are responsible for the outward flux of matter, promoting their growth, until they coa-lescence into larger ones. The local stress/strain conditions were identified to significant in-fluence the nucleation and evolution of the nano-voids. Moreover, the impurities introducedduring electrodeposition, in particular the hydrogen, also play a crucial role in “catalyzing”the nucleation of the nano-voids. In such a case, vacancy diffusion may also be in part re-sponsible for the void expansion.
We provide compelling experimental evidence for a novel failure mode in NC Ni in-volving deformation-induced amorphization during large strain plastic deformation. Thefailure of the NC Ni was found to be somewhat strain-dependent. When deformation is rela-tively small (ε=0.3), the sample fractured into two parts by sliding one part relative to anoth-er along the plane inclined approximately45°relative to the compression axis. Signatures ofmicro-void coalescence fracture, intergranular fracture and shear-slipped fracture can beidentified during TEM and SEM investigations. But when large plastic deformation was im-posed (ε=1.2), the generation of large amount of relatively “weak” amorphous structuresprovide preferable sites for crack initiation and easy means for cleavage fracture, giving riseto the change in the fracture morphology and thereby fragmentation-type failure.
引文
[1] GLEITER H. Nanocrystalline materials [J]. Progress in Materials Science,1989,33:223-315.
[2] SIEGEL R W. Nanostructured materials-mind over matter [J]. Nanostructured Materials,1994,4:121-138.
[3] GLEITER H. Nanostructured materials: Basic concepts and microstructure [J]. ActaMaterialia,2000,48:1-29.
[4] TJONG S C,CHEN H. Nanocrystalline materials and coatings [J]. Materials Science&Engineering R-Reports,2004,45:1-88.
[5] X. ZHU, R. BIRRINGER, U. HERR,H. GLEITER. X-ray diffraction studies of thestructure of nanometer-sized crystalline materials [J]. Physical Review B,1989,35:9085-9090.
[6] HERR U, JING J, BIRRINGER R, GONSER U,GLEITER H. Investigation ofnanocrystalline iron materials by M[o-umlaut]ssbauer spectroscopy [J]. Applied PhysicsLetters,1987,50:472-474.
[7] VAN SWYGENHOVEN H, CARO A,FARKAS D. Grain boundary structure and itsinfluence on plastic deformation of polycrystalline FCC metals at the nanoscale: A moleculardynamics study [J]. Scripta Materialia,2001,44:1513-1516.
[8] KUMAR K S, VAN SWYGENHOVEN H,SURESH S. Mechanical behavior ofnanocrystalline metals and alloys [J]. Acta Materialia,2003,51:5743-5774.
[9] THOMAS G J, SIEGEL R W,EASTMAN J A. Grain boundaries in nanophase palladium:High resolution electron microscopy and image simulation [J]. Scripta Metallurgica etMaterialia,1990,24:201-206.
[10] BIRRINGER R, GLEITER H, KLEIN H P,MARQUARDT P. Nanocrystalline materialsan approach to a novel solid structure with gas-like disorder?[J]. Physics Letters A,1984,102:365-369.
[11] SANDERS P G, FOUGERE G E, THOMPSON L J, EASTMAN J A,WEERTMAN J R.Improvements in the synthesis and compaction of nanocystalline materials [J].Nanostructured Materials,1997,8:243-252.
[12] SANDERS P G, EASTMAN J A,WEERTMAN J R. Elastic and tensile behavior ofnanocrystalline copper and palladium [J]. Acta Materialia,1997,45:4019-4025.
[13] SURYANARAYANA C. Mechanical alloying and milling [J]. Progress in MaterialsScience,2001,46:1-184.
[14] KOCH C C,WHITTENBERGER J D. Mechanical milling/alloying of intermetallics [J].Intermetallics,1996,4:339-355.
[15] KOCH C C. Synthesis of nanostructured materials by mechanical milling: problems andopportunities [J]. Nanostructured Materials,1997,9:13-22.
[16] PARK Y S, CHUNG K H, KIM N J,LAVERNIA E J. Microstructural investigation ofnanocrystalline bulk Al-Mg alloy fabricated by cryomilling and extrusion [J]. MaterialsScience and Engineering a-Structural Materials Properties Microstructure and Processing,2004,374:211-216.
[17] HUANG J Y, LIAO X Z, ZHU Y T, ZHOU F,LAVERNIA E J. Grain boundary structureof nanocrystalline Cu processed by cryomilling [J]. Philosophical Magazine,2003,83:1407-1419.
[18] HUANG B, JIANG H G, PEREZ R J, NUTT S R,LAVERNIA E J. The effect of Ni onthe cryogenic attritor milling of Metglas Fe78B13Si9[J]. Nanostructured Materials,1999,11:1009-1016.
[19] LU K. Nanocrystalline metals crystallized from amorphous solids: nanocrystallization,structure, and properties [J]. Materials Science and Engineering: R: Reports,1996,16:161-221.
[20] LU K, WEI W D,WANG J T. Microhardness and fracture properties of nanocrystallineNi---P alloy [J]. Scripta Metallurgica et Materialia,1990,24:2319-2323.
[21] LU K, WANG J T,WEI W D. A new method for synthesizing nanocrystalline alloys [J].Journal of Applied Physics,1991,69:522-524.
[22] NICOLAUS M M, SINNING H R,HAESSNER F. Crystallization behaviour andgeneration of a nanocrystalline state from amorphous Co33Zr67[J]. Materials Science andEngineering A,1992,150:101-112.
[23] AIHARA T AE A K, EL-ESKANDARANY M, HABAZAKI H, HASHIMOTO K, ETAL. IN: INOUE A, HASHIMOTO K, EDITORS. AMORPHOUS ANDNANOCRYSTALLINE MATERIALS;2000. P.103.[J].
[24] VALIEV R. Nanostructuring of metals by severe plastic deformation for advancedproperties [J]. Nature Materials,2004,3:511-516.
[25] VALIEV R. Materials science-Nanomaterial advantage [J]. Nature,2002,419:887-+.
[26] VALIEV R Z. Recent developments of SPD processing for fabrication of bulknanostructured materials [Z]. In: Thermec'2003, Pts1-5--CHANDRA T, TORRALBA JM,SAKAI T, ed.^eds.: Pulisher,2003:237-244
[27] VALIEV R Z,ALEKSANDROV I V. New developments in the field of fabrication ofbulk nanostructured materials by severe plastic deformation [J]. Physics of Metals andMetallography,2002,94: S4-S10.
[28] VALIEV R Z,ALEXANDROV I V. Development of severe plastic deformationtechniques for the fabrication of bulk nanostructured materials [J]. Annales DeChimie-Science Des Materiaux,2002,27:3-14.
[29] VALIEV R Z, ALEXANDROV I V, ZHU Y T,LOWE T C. Paradox of strength andductility in metals processed by severe plastic deformation [J]. Journal of Materials Research,2002,17:5-8.
[30] VALIEV R Z, ESTRIN Y, HORITA Z, LANGDON T G, ZEHETBAUER M J,ZHU Y T.Producing bulk ultrafine-grained materials by severe plastic deformation [J]. Jom,2006,58:33-39.
[31] VALIEV R Z, ISLAMGALIEV R K,ALEXANDROV I V. Bulk nanostructuredmaterials from severe plastic deformation [J]. Progress in Materials Science,2000,45:103-189.
[32] VALIEV R Z, KORZNIKOV A V,ALEXANDROV I V. Nanomaterials produced bysevere plastic deformation: An introduction [J]. Annales De Chimie-Science Des Materiaux,2002,27:1-2.
[33] VALIEV R Z, SERGUEEVA A V,MUKHERJEE A K. The effect of annealing on tensiledeformation behavior of nanostructured SPD titanium [J]. Scripta Materialia,2003,49:669-674.
[34] WEI Q, JIAO T, RAMESH K T, MA E, KECSKES L J, MAGNESS L, DOWDING R,KAZYKHANOV V U,VALIEV R Z. Mechanical behavior and dynamic failure ofhigh-strength ultrafine grained tungsten under uniaxial compression [J]. Acta Materialia,2006,54:77-87.
[35] WU S D, WANG Z G, JIANG C B, LI G Y, ALEXANDROV I V,VALIEV R Z. Shearbands in cyclically deformed ultrafine grained copper processed by ECAP [J]. MaterialsScience and Engineering A,2004,387-389:560-564.
[36] ZHILYAEV A P, LEE S, NURISLAMOVA G V, VALIEV R Z,LANGDON T G.Microhardness and microstructural evolution in pure nickel during high-pressure torsion [J].Scripta Materialia,2001,44:2753-2758.
[37] ZHILYAEV A P, NURISLAMOVA G V, KIM B K, BARO M D, SZPUNAR JA,LANGDON T G. Experimental parameters influencing grain refinement andmicrostructural evolution during high-pressure torsion [J]. Acta Materialia,2003,51:753-765.
[38] WANG Y B, LIAO X Z, ZHAO Y H, LAVERNIA E J, RINGER S P, HORITA Z,LANGDON T G,ZHU Y T. The role of stacking faults and twin boundaries in grainrefinement of a Cu-Zn alloy processed by high-pressure torsion [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2010,527:4959-4966.
[39] IWAHASHI Y, WANG J,HORITA Z. Principle of equal-channel angular pressing for theprocessing of ultrafinegrained materials [J]. Scripta Materialia,1996,35:143-146.
[40] MCMAHON G,ERB U. Bulk amorphous and nanocrystalline Ni-P alloys byelectroplating [J]. Microstructural science,1989,17:447-457.
[41] EL-SHERIK A M, ERB U,PAGE J. Microstructural evolution in pulse plated nickelelectrodeposits [J]. Surface and Coatings Technology,1997,88:70-78.
[42] EL-SHERIK A M, ERB U, PALUMBO G,AUST K T. Deviations from hall-petchbehaviour in as-prepared nanocrystalline nickel [J]. Scripta Metallurgica et Materialia,1992,27:1185-1188.
[43] ERB U. Electrodeposited nanocrystals: Synthesis, properties and industrial applications[J]. Nanostructured Materials,1995,6:533-538.
[44] ERB U, PALUMBO G, SZPUNAR B,AUST K T. Electrodeposited vs. consolidatednanocrystals: differences and similarities [J]. Nanostructured Materials,1997,9:261-270.
[45] JEONG D H, ERB U, AUST K T,PALUMBO G. The relationship between hardness andabrasive wear resistance of electrodeposited nanocrystalline Ni-P coatings [J]. ScriptaMaterialia,2003,48:1067-1072.
[46] JEONG D H, GONZALEZ F, PALUMBO G, AUST K T,ERB U. The effect of grainsize on the wear properties of electrodeposited nanocrystalline nickel coatings [J]. ScriptaMaterialia,2001,44:493-499.
[47] KARIMPOOR A A, ERB U, AUST K T,PALUMBO G. High strength nanocrystallinecobalt with high tensile ductility [J]. Scripta Materialia,2003,49:651-656.
[48] KIM S H, AUST K T, ERB U, GONZALEZ F,PALUMBO G. A comparison of thecorrosion behaviour of polycrystalline and nanocrystalline cobalt [J]. Scripta Materialia,2003,48:1379-1384.
[49] PALUMBO G, GONZALEZ F, BRENNENSTUHL A M, ERB U, SHMAYDAW,LICHTENBERGER P C. In-situ nuclear steam generator repair using electrodepositednanocrystalline nickel [J]. Nanostructured Materials,1997,9:737-746.
[50] ROBERTSON A, ERB U,PALUMBO G. Practical applications for electrodepositednanocrystalline materials [J]. Nanostructured Materials,1999,12:1035-1040.
[51] BOCKRIS J O M, AND RAZUMNEY, G. A., FUNDAMETAL ASPECTS OFELECTROCRYSTALLIZATION, P.27, PLENUM PRESS, NY (1967).[J].
[52] HALL E O. The Deformation and Ageing of Mild Steel: III Discussion of Results [J].Proceedings of the Physical Society London B,1951,64:747-753.
[53] PETCH N J. The cleavage strength of polycrystals [J]. Journal of the Iron and SteelInstitute,1953,174:25-28.
[54] GRAY I G T, LOWE T C, CADY C M, VALIEV R Z,ALEKSANDROV I V. Influenceof strain rate&temperature on the mechanical response of ultrafine-grained Cu, Ni, andAl-4Cu-0.5Zr [J]. Nanostructured Materials,1997,9:477-480.
[55] CHEN J, LU L,LU K. Hardness and strain rate sensitivity of nanocrystalline Cu [J].Scripta Materialia,2006,54:1913-1918.
[56] YOUSSEF K M, SCATTERGOOD R O, MURTY K L,KOCH C C. Ultratoughnanocrystalline copper with a narrow grain size distribution [J]. Applied Physics Letters,2004,85:929-931.
[57] HAOUAOUI M, KARAMAN I, MAIER H J,HARTWIG K T. Microstructure evolutionand mechanical behavior of bulk copper obtained by consolidation of micro-andnanopowders using equal-channel angular extrusion [J]. Metallurgical and MaterialsTransactions a-Physical Metallurgy and Materials Science,2004,35A:2935-2949.
[58] IYER R S, FREY C A, SASTRY S M L, WALLER B E,BUHRO W E. Plasticdeformation of nanocrystalline Cu and Cu-0.2wt.%B [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,1999,264:210-214.
[59] JIANG H G, ZHU Y T, BUTT D P, ALEXANDROV I V,LOWE T C. Microstructuralevolution, microhardness and thermal stability of HPT-processed Cu [J]. Materials Scienceand Engineering a-Structural Materials Properties Microstructure and Processing,2000,290:128-138.
[60] AGNEW S R, ELLIOTT B R, YOUNGDAHL C J, HEMKER K J,WEERTMAN J R.Microstructure and mechanical behavior of nanocrystalline metals [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2000,285:391-396.
[61] VALIEV R Z, KOZLOV E V, IVANOV Y F, LIAN J, NAZAROV A A,BAUDELET B.Deformation behaviour of ultra-fine-grained copper [J]. Acta Metallurgica et Materialia,1994,42:2467-2475.
[62] LU L, SHEN Y F, CHEN X H, QIAN L H,LU K. Ultrahigh strength and high electricalconductivity in copper [J]. Science,2004,304:422-426.
[63] MEYERS M A, MISHRA A,BENSON D J. Mechanical properties of nanocrystallinematerials [J]. Progress in Materials Science,2006,51:427-556.
[64] MA E. Instabilities and ductility of nanocrystalline and ultrafine-grained metals [J].Scripta Materialia,2003,49:663-668.
[65] EBRAHIMI F, ZHAI Q,KONG D. Deformation and fracture of electrodeposited copper[J]. Scripta Materialia,1998,39:315-321.
[66] HAYASHI K,ETO H. Pressure-Sintering of iron, cobalt, nickel and copper ultrafinepowders and the crystal grain size and hardness of the compacts [J]. J. Jpn. Inst. Met.,1989,53:221-226.
[67] KNAPP J A,FOLLSTAEDT D M. Hall-Petch relationship in pulsed-laser depositednickel films [J]. Journal of Materials Research,2004,19:218-227.
[68] SCHUH C A, NIEH T G,YAMASAKI T. Hall-Petch breakdown manifested in abrasivewear resistance of nanocrystalline nickel [J]. Scripta Materialia,2002,46:735-740.
[69] SCHIOTZ J,JACOBSEN K W. A maximum in the strength of nanocrystalline copper [J].Science,2003,301:1357-1359.
[70] ARGON A S,YIP S. The strongest size [J]. Philosophical Magazine Letters,2006,86:713-720.
[71] PAN Y, ZHOU Z F, FU S-Y, NIE Y,SUN C Q. FACTORS CONTROLLING THESTRONGEST SIZES IN THE INVERSE HALL-PETCH RELATIONSHIP [J]. Nano,2008,3:175-185.
[72] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Deformation mechanism crossover and mechanical behaviour in nanocrystalline materials[J]. Philosophical Magazine Letters,2003,83:385-393.
[73] VAN VLIET K J, TSIKATA S,SURESH S. Model experiments for direct visualizationof grain boundary deformation in nanocrystalline metals [J]. Applied Physics Letters,2003,83:1441-1443.
[74] LU K, LU L,SURESH S. Strengthening Materials by Engineering Coherent InternalBoundaries at the Nanoscale [J]. Science,2009,324:349-352.
[75] DAO M, LU L, SHEN Y F,SURESH S. Strength, strain-rate sensitivity and ductility ofcopper with nanoscale twins [J]. Acta Materialia,2006,54:5421-5432.
[76] LU L, SCHWAIGER R, SHAN Z W, DAO M, LU K,SURESH S. Nano-sized twinsinduce high rate sensitivity of flow stress in pure copper [J]. Acta Materialia,2005,53:2169-2179.
[77] SHEN Y F, LU L, DAO M,SURESH S. Strain rate sensitivity of Cu with nanoscaletwins [J]. Scripta Materialia,2006,55:319-322.
[78] SHEN Y F, LU L, LU Q H, JIN Z H,LU K. Tensile properties of copper with nano-scaletwins [J]. Scripta Materialia,2005,52:989-994.
[79] KOCH C C. Optimization of strength and ductility in nanocrystalline and ultrafinegrained metals [J]. Scripta Materialia,2003,49:657-662.
[80] KOCH C C, MORRIS D G, LU K,INOUE A. Ductility of nanostructured materials [J].Mrs Bulletin,1999,24:54-58.
[81] KOCH C C, YOUSSEF K M, SCATTERGOOD R O,MURTY K L. Breakthroughs inOptimization of Mechanical Properties of Nanostructured Metals and Alloys [J]. AdvancedEngineering Materials,2005,7:787-794.
[82] WANG Y M, WANG K, PAN D, LU K, HEMKER K J,MA E. Microsample tensiletesting of nanocrystalline copper [J]. Scripta Materialia,2003,48:1581-1586.
[83] NIEMAN G W, WEERTMAN J R,SIEGEL R W. Mechanical behavior ofnanocrystalline Cu and Pd [J]. Journal of Materials Research,1991,6:1012-1027.
[84] LEGROS M, ELLIOTT B R, RITTNER M N, WEERTMAN J R,HEMKER K J.Microsample tensile testing of nanocrystalline metals [J]. Philosophical Magazine a-Physicsof Condensed Matter Structure Defects and Mechanical Properties,2000,80:1017-1026.
[85] WU X J, DU L G, ZHANG H F, LIU J F, ZHOU Y S, LI Z Q, XIONG L Y,BAI Y L.Synthesis and tensile property of nanocrystalline metal copper [J]. Nanostructured Materials,1999,12:221-224.
[86] CHENG S, MA E, WANG Y M, KECSKES L J, YOUSSEF K M, KOCH C C,TROCIEWITZ U P,HAN K. Tensile properties of in situ consolidated nanocrystalline Cu [J].Acta Materialia,2005,53:1521-1533.
[87] WANG Y M,MA E. Temperature and strain rate effects on the strength and ductility ofnanostructured copper [J]. Applied Physics Letters,2003,83:3165-3167.
[88] CONRAD H,NARAYAN J. Mechanisms for grain size hardening and softening in Zn[J]. Acta Materialia,2002,50:5067-5078.
[89] YOUSSEF K M, SCATTERGOOD R O, MURTY K L, HORTON J A,KOCH C C.Ultrahigh strength and high ductility of bulk nanocrystalline copper [J]. Applied PhysicsLetters,2005,87:
[90] SCHWAIGER R, MOSER B, DAO M, CHOLLACOOP N,SURESH S. Some criticalexperiments on the strain-rate sensitivity of nanocrystalline nickel [J]. Acta Materialia,2003,51:5159-5172.
[91] DALLA TORRE F, VAN SWYGENHOVEN H,VICTORIA M. Nanocrystallineelectrodeposited Ni: microstructure and tensile properties [J]. Acta Materialia,2002,50:3957-3970.
[92] WEERTMAN J R, FARKAS D, HEMKER K, KUNG H, MAYO M, MITRA R,VANSWYGENHOVEN H. Structure and mechanical behavior of bulk nanocrystalline materials[J]. Mrs Bulletin,1999,24:44-50.
[93] LI H,EBRAHIMI F. Transition of deformation and fracture behaviors in nanostructuredface-centered-cubic metals [J]. Applied Physics Letters,2004,84:4307-4309.
[94] WANG L, HAN X, LIU P, YUE Y, ZHANG Z,MA E. In Situ Observation ofDislocation Behavior in Nanometer Grains [J]. Physical Review Letters,2010,105:
[95] WU X L, ZHU Y T, WEI Y G,WEI Q. Strong Strain Hardening in NanocrystallineNickel [J]. Physical Review Letters,2009,103:
[96] WANG Y, CHEN M, ZHOU F,MA E. High tensile ductility in a nanostructured metal[J]. Nature,2002,419:912-915.
[97] GIANOLA D S, VAN PETEGEM S, LEGROS M, BRANDSTETTER S, VANSWYGENHOVEN H,HEMKER K J. Stress-assisted discontinuous grain growth and itseffect on the deformation behavior of nanocrystalline aluminum thin films [J]. ActaMaterialia,2006,54:2253-2263.
[98] GU C, LIAN J, JIANG Z,JIANG Q. Enhanced tensile ductility in an electrodepositednanocrystalline Ni [J]. Scripta Materialia,2006,54:579-584.
[99] LU L, CHEN X, HUANG X,LU K. Revealing the Maximum Strength in NanotwinnedCopper [J]. Science,2009,323:607-610.
[100] LI H Q,EBRAHIMI F. Ductile-to-brittle transition in nanocrystalline metals [J].Advanced Materials,2005,17:1969-1971.
[101] HUGO R C, KUNG H, WEERTMAN J R, MITRA R, KNAPP J A,FOLLSTAEDT DM. In-situ TEM tensile testing of DC magnetron sputtered and pulsed laser deposited Ni thinfilms [J]. Acta Materialia,2003,51:1937-1943.
[102] HASNAOUI A, VAN SWYGENHOVEN H,DERLET P M. Dimples onnanocrystalline fracture surfaces as evidence for shear plane formation [J]. Science,2003,300:1550-1552.
[103] SHAN Z, KNAPP J A, FOLLSTAEDT D M, STACH E A, WIEZOREK J M K,MAOS X. Inter-and intra-agglomerate fracture in nanocrystalline nickel [J]. Physical ReviewLetters,2008,100:
[104] KUMAR K S, SURESH S, CHISHOLM M F, HORTON J A,WANG P. Deformationof electrodeposited nanocrystalline nickel [J]. Acta Materialia,2003,51:387-405.
[105] DALLA TORRE F, SPATIG P, SCHAUBLIN R,VICTORIA M. Deformationbehaviour and microstructure of nanocrystalline electrodeposited and high pressure torsionednickel [J]. Acta Materialia,2005,53:2337-2349.
[106] WANG Y M, HAMZA A V,MA E. Temperature-dependent strain rate sensitivity andactivation volume of nanocrystalline Ni [J]. Acta Materialia,2006,54:2715-2726.
[107] WANG Y M, HAMZA A V,MA E. Activation volume and density of mobiledislocations in plastically deforming nanocrystalline Ni [J]. Applied Physics Letters,2005,86:241917-3.
[108] WEI Q, CHENG S, RAMESH K T,MA E. Effect of nanocrystalline and ultrafine grainsizes on the strain rate sensitivity and activation volume: fcc versus bcc metals [J]. MaterialsScience and Engineering a-Structural Materials Properties Microstructure and Processing,2004,381:71-79.
[109] LU L, LI S X,LU K. An abnormal strain rate effect on tensile behavior innanocrystalline copper [J]. Scripta Materialia,2001,45:1163-1169.
[110] CARREKER JR R P,HIBBARD JR W R. Tensile deformation of high-purity copper asa function of temperature, strain rate, and grain size [J]. Acta Metallurgica,1953,1:654-663.
[111] ZEHETBAUER M,SEUMER V. Cold work hardening in stages IV and V of F.C.C.metals—I. Experiments and interpretation [J]. Acta Metallurgica et Materialia,1993,41:577-588.
[112] BOCHNIAK W. Mode of deformation and the Cottrell-Strokes law in F.C.C. singlecrystals [J]. Acta Metallurgica et Materialia,1995,43:225-233.
[113] DAO M, LU L, ASARO R J, DE HOSSON J T M,MA E. Toward a quantitativeunderstanding of mechanical behavior of nanocrystalline metals [J]. Acta Materialia,2007,55:4041-4065.
[114] LU L, DAO M, ZHU T,LI J. Size dependence of rate-controlling deformationmechanisms in nanotwinned copper [J]. Scripta Materialia,2009,60:1062-1066.
[115] CHENG S, SPENCER J A,MILLIGAN W W. Strength and tension/compressionasymmetry in nanostructured and ultrafine-grain metals [J]. Acta Materialia,2003,51:4505-4518.
[116] ASARO R J,SURESH S. Mechanistic models for the activation volume and ratesensitivity in metals with nanocrystalline grains and nano-scale twins [J]. Acta Materialia,2005,53:3369-3382.
[117] VAN SWYGENHOVEN H, DERLET P M,FROSETH A G. Nucleation andpropagation of dislocations in nanocrystalline fcc metals [J]. Acta Materialia,2006,54:1975-1983.
[118] MA E. Eight routes to improve the tensile ductility of bulk nanostructured metals andalloys [J]. Jom,2006,58:49-53.
[119] WANG Y M,MA E. Three strategies to achieve uniform tensile deformation in ananostructured metal [J]. Acta Materialia,2004,52:1699-1709.
[120] DERLET P M, HASNAOUI A,VAN SWYGENHOVEN H. Atomistic simulations asguidance to experiments [J]. Scripta Materialia,2003,49:629-635.
[121] VAN SWYGENHOVEN H. Polycrystalline materials-Grain boundaries anddislocations [J]. Science,2002,296:66-67.
[122] VAN SWYGENHOVEN H, SPACZER M,CARO A. Microscopic description ofplasticity in computer generated metallic nanophase samples: A comparison between Cu andNi [J]. Acta Materialia,1999,47:3117-3126.
[123] SCHIOTZ J, VEGGE T, DI TOLLA F D,JACOBSEN K W. Atomic-scale simulationsof the mechanical deformation of nanocrystalline metals [J]. Physical Review B,1999,60:11971-11983.
[124] SCHI TZ J, DI TOLLA F D,JACOBSEN K W. Softening of nanocrystalline metals atvery small grain sizes [J]. Nature,1998,391:561-563.
[125] WOLF D, YAMAKOV V, PHILLPOT S R, MUKHERJEE A,GLEITER H.Deformation of nanocrystalline materials by molecular-dynamics simulation: relationship toexperiments?[J]. Acta Materialia,2005,53:1-40.
[126] YAMAKOV V, WOLF D, PHILLPOT S R,GLEITER H. Deformation twinning innanocrystalline Al by molecular dynamics simulation [J]. Acta Materialia,2002,50:5005-5020.
[127] YAMAKOV V, WOLF D, PHILLPOT S R,GLEITER H. Dislocation-dislocation anddislocation-twin reactions in nanocrystalline Al by molecular dynamics simulation [J]. ActaMaterialia,2003,51:4135-4147.
[128] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Deformation-mechanism map for nanocrystalline metals by molecular-dynamics simulation[J]. Nature Materials,2004,3:43-47.
[129] VAN SWYGENHOVEN H, DERLET P M,FROSETH A G. Stacking fault energiesand slip in nanocrystalline metals [J]. Nature Materials,2004,3:399-403.
[130] FARKAS D, VAN PETEGEM S, DERLET P M,VAN SWYGENHOVEN H.Dislocation activity and nano-void formation near crack tips in nanocrystalline Ni [J]. ActaMaterialia,2005,53:3115-3123.
[131] FARKAS D, VAN SWYGENHOVEN H,DERLET P M. Intergranular fracture innanocrystalline metals [J]. Physical Review B,2002,66:
[132] CAO A,WEI Y. Atomistic simulations of crack nucleation and intergranular fracture inbulk nanocrystalline nickel [J]. Physical Review B,2007,76:
[133] FARKAS D, WILLEMANN M,HYDE B. Atomistic mechanisms of fatigue innanocrystalline metals [J]. Physical Review Letters,2005,94:
[134] DAVILA L P, ERHART P, BRINGA E M, MEYERS M A, LUBARDA V A,SCHNEIDER M S, BECKER R,KUMAR M. Atomistic modeling of shock-induced voidcollapse in copper [J]. Applied Physics Letters,2005,86:
[135] LUBARDA V A, SCHNEIDER M S, KALANTAR D H, REMINGTON BA,MEYERS M A. Void growth by dislocation emission [J]. Acta Materialia,2004,52:1397-1408.
[136] MEYERS M A, TRAIVIRATANA S, LUBARDA V A, BENSON D J,BRINGA E M.The role of dislocations in the growth of nanosized voids in ductile failure of metals [J]. Jom,2009,61:35-41.
[137] TRAIVIRATANA S, BRINGA E M, BENSON D J,MEYERS M A. Void growth inmetals: Atomistic calculations [J]. Acta Materialia,2008,56:3874-3886.
[138] VAN SWYGENHOVEN H,DERLET P A. Grain-boundary sliding in nanocrystallinefcc metals [J]. Physical Review B,2001,64:
[139] SERGUEEVA A V, MARA N A, KRASILNIKOV N A, VALIEV R Z,MUKHERJEE AK. Cooperative grain boundary sliding in nanocrystalline materials [J]. PhilosophicalMagazine,2006,86:5797-5804.
[140] IVANISENKO Y, KURMANAEVA L, WEISSMUELLER J, YANG K, MARKMANNJ, ROESNER H, SCHERER T,FECHT H J. Deformation mechanisms in nanocrystallinepalladium at large strains [J]. Acta Materialia,2009,57:3391-3401.
[141] CHINH N Q, SZOMMER P, HORITA Z,LANGDON T G. Experimental evidence forgrain-boundary sliding in ultrafine-grained aluminum processed by severe plasticdeformation [J]. Advanced Materials,2006,18:34-39.
[142] BOBYLEV S V,OVID'KO I A. Nanograin nucleation initiated by intergrain slidingand/or lattice slip in nanomaterials [J]. Applied Physics Letters,2008,92:
[143] OVID'KO I A,SHEINERMAN A G. Enhanced ductility of nanomaterials throughoptimization of grain boundary sliding and diffusion processes [J]. Acta Materialia,2009,57:2217-2228.
[144] KE M, HACKNEY S A, MILLIGAN W W,AIFANTIS E C. Observation andmeasurement of grain rotation and plastic strain in nanostructured metal thin films [J].Nanostructured Materials,1995,5:689-697.
[145] SHAN Z, STACH E A, WIEZOREK J M K, KNAPP J A, FOLLSTAEDT D M,MAOS X. Grain Boundary-Mediated Plasticity in Nanocrystalline Nickel [J]. Science,2004,305:654-657.
[146] JIN M, MINOR A M, STACH E A,MORRIS J W. Direct observation ofdeformation-induced grain growth during the nanoindentation of ultrafine-grained Al atroom temperature [J]. Acta Materialia,2004,52:5381-5387.
[147] WANG Y B, LI B Q, SUI M L,MAO S X. Deformation-induced grain rotation andgrowth in nanocrystalline Ni [J]. Applied Physics Letters,2008,92:
[148] LIAO X Z, KILMAMETOV A R, VALIEV R Z, GAO H S, LI X D, MUKHERJEE AK, BINGERT J F,ZHU Y T. High-pressure torsion-induced grain growth in electrodepositednanocrystalline Ni [J]. Applied Physics Letters,2006,88:
[149] WANG Y B, HO J C, CAO Y, LIAO X Z, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P,ZHU Y T. Dislocation density evolution during high pressure torsion of ananocrystalline Ni-Fe alloy [J]. Applied Physics Letters,2009,94:
[150] NI S, WANG Y B, LIAO X Z, ALHAJERI S N, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P, LANGDON T G,ZHU Y T. Grain growth and dislocation density evolution ina nanocrystalline Ni-Fe alloy induced by high-pressure torsion [J]. Scripta Materialia,2011,64:327-330.
[151] SHAN Z W, WIEZOREK J M K, STACH E A, FOLLSTAEDT D M, KNAPP JA,MAO S X. Dislocation dynamics in nanocrystalline nickel [J]. Physical Review Letters,2007,98:
[152] WANG Y M, OTT R T, HAMZA A V, BESSER M F, ALMER J,KRAMER M J.Achieving Large Uniform Tensile Ductility in Nanocrystalline Metals [J]. Physical ReviewLetters,2010,105:
[153] BUDROVIC Z, VAN SWYGENHOVEN H, DERLET P M, VAN PETEGEMS,SCHMITT B. Plastic deformation with reversible peak broadening in nanocrystallinenickel [J]. Science,2004,304:273-276.
[154] WU X, MA E,ZHU Y T. Deformation defects in nanocrystalline nickel [J]. Journal ofMaterials Science,2007,42:1427-1432.
[155] WU X-L,MA E. Dislocations in nanocrystalline grains [J]. Applied Physics Letters,2006,88:
[156] ZHU Y T, LIAO X Z,WU X L. Deformation twinning in bulk nanocrystalline metals:Experimental observations [J]. Jom,2008,60:60-64.
[157] CHEN M, MA E, HEMKER K J, SHENG H, WANG Y,CHENG X. DeformationTwinning in Nanocrystalline Aluminum [J]. Science,2003,300:1275-1277.
[158] HE J H, CHUNG K H, LIAO X Z, ZHU Y T,LAVERNIA E J. Mechanicalmilling-induced deformation twinning in Fcc materials with high stacking fault energy [J].Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,2003,34:707-712.
[159] LIAO X Z, ZHAO Y H, SRINIVASAN S G, ZHU Y T, VALIEV R Z,GUNDEROV DV. Deformation twinning in nanocrystalline copper at room temperature and low strain rate[J]. Applied Physics Letters,2004,84:592-594.
[160] LIAO X Z, ZHOU F, LAVERNIA E J, SRINIVASAN S G, BASKES M I, HE DW,ZHU Y T. Deformation mechanism in nanocrystalline Al: Partial dislocation slip [J].Applied Physics Letters,2003,83:632-634.
[161] ROSNER H, MARKMANN J,WEISSMULLER J. Deformation twinning innanocrystalline Pd [J]. Philosophical Magazine Letters,2004,84:321-334.
[162] ZHU Y T,LANGDON T G. Influence of grain size on deformation mechanisms: Anextension to nanocrystalline materials [J]. Materials Science and Engineering a-StructuralMaterials Properties Microstructure and Processing,2005,409:234-242.
[163] TRIMBY P W. Orientation mapping of nanostructured materials using transmissionKikuchi diffraction in the scanning electron microscope [J]. Ultramicroscopy,2012,120:16-24.
[164] TRIMBY P W, CAO Y, CHEN Z, HAN S, HEMKER K J, LIAN J, LIAO X,ROTTMANN P, SAMUDRALA S, SUN J, WANG J T, WHEELER J,CAIRNEY J M.Characterizing deformed ultrafine-grained and nanocrystalline materials using transmissionKikuchi diffraction in a scanning electron microscope [J]. Acta Materialia,2014,62:69-80.
[165] WU X, ZHU Y T, CHEN M W,MA E. Twinning and stacking fault formation duringtensile deformation of nanocrystalline Ni [J]. Scripta Materialia,2006,54:1685-1690.
[166] MA E. Watching the nanograins roll [J]. Science,2004,305:623-624.
[167] ZHU Y T,LIAO X Z. Nanostructured metals-Retaining ductility [J]. Nature Materials,2004,3:351-352.
[168] WANG Y B, HO J C, LIAO X Z, LI H Q, RINGER S P,ZHU Y T. Mechanism of graingrowth during severe plastic deformation of a nanocrystalline Ni-Fe alloy [J]. AppliedPhysics Letters,2009,94:
[169] SANSOZ F,DUPONT V. Grain growth behavior at absolute zero duringnanocrystalline metal indentation [J]. Applied Physics Letters,2006,89:
[170] JIANG Z H, LIU X L, LI G Y, JIANG Q,LIAN J S. Strain rate sensitivity of ananocrystalline Cu synthesized by electric brush plating [J]. Applied Physics Letters,2006,88:
[171] CHEN M W, MA E, HEMKER K J, SHENG H W, WANG Y M,CHENG X M.Deformation twinning in nanocrystalline aluminum [J]. Science,2003,300:1275-1277.
[172] VAN SWYGENHOVEN H, DERLET P M,HASNAOUI A. Atomic mechanism fordislocation emission from nanosized grain boundaries [J]. Physical Review B,2002,66:
[173] VAN SWYGENHOVEN H,WEERTMAN J R. Deformation in nanocrystalline metals[J]. Materials Today,2006,9:24-31.
[174] NI S, WANG Y B, LIAO X Z, FIGUEIREDO R B, LI H Q, ZHAO Y H, LAVERNIAE J, RINGER S P, LANGDON T G,ZHU Y T. Strain softening in nanocrystalline Ni-Fe alloyinduced by large HPT revolutions [J]. Materials Science and Engineering a-StructuralMaterials Properties Microstructure and Processing,2011,528:4807-4811.
[175] NI S, WANG Y B, LIAO X Z, ALHAJERI S N, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P, LANGDON T G,ZHU Y T. Strain hardening and softening in a nanocrystallineNi-Fe alloy induced by severe plastic deformation [J]. Materials Science and Engineeringa-Structural Materials Properties Microstructure and Processing,2011,528:3398-3403.
[176] PAN D, KUWANO S, FUJITA T,CHEN M. Ultra-large room-temperature compressiveplasticity of a nanocrystalline metal [J]. Nano Letters,2007,7:2108-2111.
[177] CHENG S, ZHAO Y, GUO Y, LI Y, WEI Q, WANG X L, REN Y, LIAW P K, CHOOH,LAVERNIA E J. High Plasticity and Substantial Deformation in Nanocrystalline NiFeAlloys Under Dynamic Loading [J]. Advanced Materials,2009,21:5001-5004.
[178] WANG Y M,MA E. On the origin of ultrahigh cryogenic strength of nanocrystallinemetals [J]. Applied Physics Letters,2004,85:2750-2752.
[179] WEI Q, CHENG S, RAMESH K T,MA E. Effect of nanocrystalline and ultrafine grainsizes on the strain rate sensitivity and activation volume: fcc versus bcc metals [J]. MaterialsScience and Engineering A,2004,381:71-79.
[180] HIRTH J P,LOTHE J. Theroy of dislcoations [J]. Wiley, New York,2nd edn.,1982: pp.159,752.
[181] GU C, LIAN J,JIANG Q. Layered nanostructured Ni with modulated hardnessfabricated by surfactant-assistant electrodeposition [J]. Scripta Materialia,2007,57:233-236.
[182] GU C, LIAN J,JIANG Z. High Strength Nanocrystalline Ni-Co Alloy with EnhancedTensile Ductility [J]. Advanced Engineering Materials,2006,8:252-256.
[183] WANG Y,MA E. On the origin of ultrahigh cryogenic strength of nanocrystallinemetals [J]. Applied Physics Letters,2004,85:2750-2752.
[184] LIAO X Z, ZHOU F, LAVERNIA E J, HE D W,ZHU Y T. Deformation twins innanocrystalline Al [J]. Applied Physics Letters,2003,83:5062-5064.
[185] ZHU Y T, LIAO X Z, SRINIVASAN S G, ZHAO Y H, BASKES M I, ZHOUF,LAVERNIA E J. Nucleation and growth of deformation twins in nanocrystalline aluminum[J]. Applied Physics Letters,2004,85:5049-5051.
[186] ZHU Y T, NARAYAN J, HIRTH J P, MAHAJAN S, WU X L,LIAO X Z. Formation ofsingle and multiple deformation twins in nanocrystalline fcc metals [J]. Acta Materialia,2009,57:3763-3770.
[187] LIAO X Z, HUANG J Y, ZHU Y T, ZHOU F,LAVERNIA E J. Nanostructures anddeformation mechanisms in a cryogenically ball-milled Al-Mg alloy [J]. PhilosophicalMagazine,2003,83:3065-3075.
[188] VAN SWYGENHOVEN H, DERLET P M,FR SETH A G. Stacking fault energies andslip in nanocrystalline metals [J]. Nature Materials,01Jun2004,3:399-403.
[189] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Dislocation processes in the deformation of nanocrystalline aluminium bymolecular-dynamics simulation [J]. Nature Materials,2002,1:45-48.
[190] WANG Z W, WANG Y B, LIAO X Z, ZHAO Y H, LAVERNIA E J, ZHU Y T,HORITA Z,LANGDON T G. Influence of stacking fault energy on deformation mechanismand dislocation storage capacity in ultrafine-grained materials [J]. Scripta Materialia,2009,60:52-55.
[191] NI S, WANG Y B, LIAO X Z, FIGUEIREDO R B, LI H Q, RINGER S P, LANGDONT G,ZHU Y T. The effect of dislocation density on the interactions between dislocations andtwin boundaries in nanocrystalline materials [J]. Acta Materialia,2012,60:3181-3189.
[192] VALIEV R, GERTSMAN V Y,KAIBYSHEV O. Grain boundary structure andproperties under external influences [J]. Physica status solidi (a),1986,97:11-56.
[193] ZHU Y T, HUANG J Y, GUBICZA J, UNGAR T, WANG Y M, MA E,VALIEV R Z.Nanostructures in Ti processed by severe plastic deformation [J]. Journal of MaterialsResearch,2003,18:1908-1917.
[194] VALIEV R, MISHRAL R, GROZAL J,MUKHERJEE A. Processing of nanostructurednickel by severe plastic deformation consolidation of ball-milled powder [J]. Scriptamaterialia,1996,34:1443-1448.
[195] MISHIN O, GERTSMAN V Y, VALIEV R,GOTTSTEIN G. Grain boundarydistribution and texture in ultrafine-grained copper produced by severe plastic deformation[J]. Scripta Materialia,1996,35:873-878.
[196] FEDOROV A A, GUTKIN M Y,OVID'KO I A. Transformations of grain boundarydislocation pile-ups in nano-and polycrystalline materials [J]. Acta Materialia,2003,51:887-898.
[197] HUANG J Y, ZHU Y T, JIANG H,LOWE T C. Microstructures and dislocationconfigurations in nanostructured Cu processed by repetitive corrugation and straightening [J].Acta Materialia,2001,49:1497-1505.
[198] WU X L,ZHU Y T. Partial-dislocation-mediated processes in nanocrystalline Ni withnonequilibrium grain boundaries [J]. Applied Physics Letters,2006,89:
[199] LIAN J S, GU C D, JIANG Q,JIANG Z H. Strain rate sensitivity offace-centered-cubic nanocrystalline materials based on dislocation deformation [J]. Journalof Applied Physics,2006,99:
[200] GUTKIN M Y, OVID'KO I A,SKIBA N V. Crossover from grain boundary sliding torotational deformation in nanocrystalline materials [J]. Acta Materialia,2003,51:4059-4071.
[201] KLEMENT W, WILLENS R,DUWEZ P. Non-crystalline structure in solidifiedgold–silicon alloys [J].1960:
[202] HE Y, POON S,SHIFLET G. Synthesis and properties of metallic glasses that containaluminum [J]. Science,1988,241:1640-1642.
[203] JANG J,KOCH C. Amorphization and disordering of the Ni3Al ordered intermetallicby mechanical milling [J]. J. Mater. Res,1990,5:498-509.
[204] WINTERS R R,HAMMACK W S. Pressure-induced amorphization of R-Al5Li3Cu: astructural relation among amorphous metals, quasi-crystals, and curved space [J]. Science,1993,260:202-204.
[205] INOUE A. Stabilization of metallic supercooled liquid and bulk amorphous alloys [J].Acta Materialia,2000,48:279-306.
[206] HOFMANN D C, SUH J-Y, WIEST A, DUAN G, LIND M-L, DEMETRIOU MD,JOHNSON W L. Designing metallic glass matrix composites with high toughness andtensile ductility [J]. Nature,2008,451:1085-U3.
[207] WANG W-H, DONG C,SHEK C. Bulk metallic glasses [J]. Materials Science andEngineering: R: Reports,2004,44:45-89.
[208] GREER A L. Metallic glasses [J]. Science,1995,267:1947-1953.
[209] FECHT H. Defect-induced melting and solid-state amorphization [J]. Nature,1992,356:133-135.
[210] BHAT M H, MOLINERO V, SOIGNARD E, SOLOMON V C, SASTRY S, YARGERJ L,ANGELL C A. Vitrification of a monatomic metallic liquid [J]. Nature,2007,448:787-U3.
[211] HOLZ M, ZIEMANN P,BUCKEL W. Direct evidence for amorphization of puregallium by low-temperature ion irradiation [J]. Physical review letters,1983,51:1584.
[212] VO VAN H,ODAGAKI T. Glass Formation and Thermodynamics of SupercooledMonatomic Liquids [J]. Journal of Physical Chemistry B,2011,115:6946-6956.
[213] KUNDIG A A, LOFFLER J F, JOHNSON W L, UGGOWITZER PJ,THIYAGARAJAN P. Influence of decomposition on the thermal stability of undercooledZr-Ti-Cu-Ni-Al alloys [J]. Scripta Materialia,2001,44:1269-1273.
[214] IKEDA H, QI Y, CAGIN T, SAMWER K, JOHNSON W L,GODDARD W A. Strainrate induced amorphization in metallic nanowires [J]. Physical Review Letters,1999,82:2900-2903.
[215] SWAMY V, KUZNETSOV A, DUBROVINSKY L S, MCMILLAN P F,PRAKAPENKA V B, SHEN G,MUDDLE B C. Size-dependent pressure-inducedamorphization in nanoscale TiO2[J]. Physical review letters,2006,96:135702.
[216] MELDRUM A, BOATNER L A,EWING R C. Nanocrystalline zirconia can beamorphized by ion irradiation [J]. Physical Review Letters,2002,88:
[217] JOHANNESSEN B, KLUTH P, LLEWELLYN D, FORAN G J, COOKSOND,RIDGWAY M C. Amorphization of embedded Cu nanocrystals by ion irradiation [J].Applied physics letters,2007,90:073119.
[218] FECHT H. Thermodynamic Properties of Amorphous Solids--Glass Formation andGlass Transition--(Overview)[J]. Materials transactions-JIM,1995,36:777-777.
[219] MA E. Amorphization in mechanically driven material systems [J]. Scripta materialia,2003,49:941-946.
[220] CHEN M, MCCAULEY J W,HEMKER K J. Shock-Induced Localized Amorphizationin Boron Carbide [J]. Science,2003,299:1563-1566.
[221] COURTNEY T H. Mechanical behavior of materials [M]. Place Published: WavelandPress,2005.
[222] CHENG S, ZHAO Y, WANG Y, LI Y, WANG X-L, LIAW P K,LAVERNIA E J.Structure Modulation Driven by Cyclic Deformation in Nanocrystalline NiFe [J]. PhysicalReview Letters,2010,104:
[223] HUANG J Y, ZHU Y T, LIAO X Z,VALIEV R Z. Amorphization of TiNi induced byhigh-pressure torsion [J]. Philosophical Magazine Letters,2004,84:183-190.
[224] LIN Z, ZHUO M, SUN Z, VEYSSI RE P,ZHOU Y. Amorphization by dislocationaccumulation in shear bands [J]. Acta Materialia,2009,57:2851-2857.
[225] WU X, TAO N, HONG Y, LU J,LU K. Localized solid-state amorphization at grainboundaries in a nanocrystalline Al solid solution subjected to surface mechanical attrition [J].Journal of Physics D: Applied Physics,2005,38:4140.
[226] HUANG J, ZHU Y, LIAO X,VALIEV R. Amorphization of TiNi induced byhigh-pressure torsion [J]. Philosophical magazine letters,2004,84:183-190.
[227] SAGEL A, WANDERKA N, WUNDERLICH R, SCHUBERT-BISCHOFF P,FECHTH-J. Early stages of solid-state amorphization reaction during mechanical alloying of amulticomponent Zr-powder mixture [J]. Scripta materialia,1997,38:163-169.
[228] YAMADA K,KOCH C C. The influence of mill energy and temperature on thestructure of the TiNi intermetallic after mechanical attrition [J]. Journal of materials research,1993,8:1317-1326.
[229] HUANG J Y, YASUDA H,MORI H. Deformation-induced amorphization inball-milled silicon [J]. Philosophical Magazine Letters,1999,79:305-314.
[230] FAN G, GUO F, HU Z, QUAN M,LU K. Amorphization of selenium induced byhigh-energy ball milling [J]. Physical Review B,1997,55:11010.
[231] BENEDICTUS R, HAN K, TRAEHOLT C, B TTGER A,MITTEMEIJER E. Solidstate amorphization in Ni–Ti systems: the effect of structure on the kinetics of interface andgrain-boundary amorphization [J]. Acta materialia,1998,46:5491-5508.
[232] WU Y,XU Y. Lattice-distortion-induced amorphization in indented [110] silicon [J].Journal of materials research,1999,14:682-687.
[233] WU Y, YANG X,XU Y. Cross-sectional electron microscopy observation on theamorphized indentation region in [001] single-crystal silicon [J]. Acta materialia,1999,47:2431-2436.
[234] LI M. Defect-induced topological order-to-disorder transitions in two-dimensionalbinary substitutional solid solutions: A molecular dynamics study [J]. Physical Review B,2000,62:13979-13995.
[235] OVID'KO I A,REIZIS A B. Effect of elastic distortions on solid-state amorphization atgrain boundaries and dislocations [J]. Journal of Physics D-Applied Physics,1999,32:2833-2840.
[236] KINGMA K J, MEADE C, HEMLEY R J, MAO H-K,VEBLEN D R. Microstructuralobservations of alpha-quartz amorphization [J]. Science,1993,259:666-669.
[237] OVID’KO I. Review on the fracture processes in nanocrystalline materials [J]. Journalof materials science,2007,42:1694-1708.
[238] BRINGA E M, TRAIVIRATANA S,MEYERS M A. Void initiation in fcc metals:Effect of loading orientation and nanocrystalline effects [J]. Acta Materialia,2010,58:4458-4477.
[239] MYERS S, BIRNBAUM H, CORBETT J, DELEO G, ESTREICHER S, HALLER E,JENA P, JOHNSON N, KIRCHHEIM R,PEARTON S. Hydrogen interactions with defectsin crystalline solids [J]. Reviews of Modern Physics,1992,64:559-617.
[240] CUITINO A,ORTIZ M. Ductile fracture by vacancy condensation in fcc single crystals[J]. Acta materialia,1996,44:427-436.
[241] RICE J, JOHNSON M,KANNINEN M. Inelastic behavior of solids [J]. McGraw-Hill,New York,1970,641:
[242] AHN D, SOFRONIS P, KUMAR M, BELAK J,MINICH R. Void growth bydislocation-loop emission [J]. Journal of applied physics,2007,101:063514.
[243] SEPPALA E T, BELAK J,RUDD R E. Onset of void coalescence during dynamicfracture of ductile metals [J]. Physical Review Letters,2004,93:
[244] VORONO G. Nouvelles applications des paramètres continus à la théorie des formesquadratiques. Deuxième mémoire. Recherches sur les parallélloèdres primitifs [J]. Journalfür die reine und angewandte Mathematik,1908,134:198-287.
[245] DAW M S. Model of metallic cohesion: The embedded-atom method [J]. PhysicalReview B,1989,39:7441.
[246] RIBBE J, SCHMITZ G, R SNER H, LAPOVOK R, ESTRIN Y, WILDE G,DIVINSKIS V. Effect of back pressure during equal-channel angular pressing on deformation-inducedporosity in copper [J]. Scripta Materialia,2013,68:925-928.
[247] LAPOVOK R. Damage evolution under severe plastic deformation [J]. InternationalJournal of fracture,2002,115:159-172.
[248] ZHANG Z, ZHANG H, PAN X, DAS J,ECKERT J. Effect of aspect ratio on thecompressive deformation and fracture behaviour of Zr-based bulk metallic glass [J].Philosophical magazine letters,2005,85:513-521.
[249] DIVINSKI S V, RIBBE J, BAITHER D, SCHMITZ G, REGLITZ G, R SNER H,SATO K, ESTRIN Y,WILDE G. Nano-and micro-scale free volume in ultrafine grainedCu–1wt.%Pb alloy deformed by equal channel angular pressing [J]. Acta Materialia,2009,57:5706-5717.
[250] RIBBE J, BAITHER D, SCHMITZ G,DIVINSKI S V. Network of porosity formed inultrafine-grained copper produced by equal channel angular pressing [J]. Physical reviewletters,2009,102:165501.
[251] DIVINSKI S V, RIBBE J, REGLITZ G, ESTRIN Y,WILDE G. Percolating network ofultrafast transport channels in severely deformed nanocrystalline metals [J]. Journal ofApplied Physics,2009,106:063502.
[252] RIBBE J, BAITHER D, SCHMITZ G,DIVINSKI S V. Ultrafast diffusion and internalporosity in ultrafine-grained copper–lead alloy prepared by equal channel angular pressing[J]. Scripta Materialia,2009,61:129-132.
[253] EBRAHIMI F, LISCANO A, KONG D, ZHAI Q,LI H. Fracture of bulk face centeredcubic (FCC) metallic nanostructures [J]. Rev. Adv. Mater. Sci,2006,13:33-40.
[254] OVID'KO I A,SHEINERMAN A G. Nanocrack generation at dislocation-disclinationconfigurations in nanocrystalline metals and ceramics [J]. Physical Review B,2008,77:
[255] OVID'KO I A. Review on the fracture processes in nanocrystalline materials [J].Journal of Materials Science,2007,42:1694-1708.
[256] OVID'KO I A,SHEINERMAN A G. Suppression of nanocrack generation innanocrystalline materials under superplastic deformation [J]. Acta Materialia,2005,53:1347-1359.
[257] LU G,KAXIRAS E. Hydrogen embrittlement of aluminum: The crucial role ofvacancies [J]. Physical review letters,2005,94:155501.
[258] CHANDLER M Q, HORSTEMEYER M, BASKES M, WAGNER G, GULLETTP,JELINEK B. Hydrogen effects on nanovoid nucleation at nickel grain boundaries [J]. ActaMaterialia,2008,56:619-631.
[259] CHANDLER M Q, HORSTEMEYER M, BASKES M, GULLETT P, WAGNERG,JELINEK B. Hydrogen effects on nanovoid nucleation in face-centered cubicsingle-crystals [J]. Acta Materialia,2008,56:95-104.
[260] NEERAJ T, SRINIVASAN R,LI J. Hydrogen embrittlement of ferritic steels:Observations on deformation microstructure, nanoscale dimples and failure by nanovoiding[J]. Acta Materialia,2012,60:5160-5171.
[261] NAGUMO M. Hydrogen related failure of steels–a new aspect [J]. Materials Scienceand Technology,2004,20:940-950.
[262] WURSCHUM R, HERTH S,BROSSMANN U. Diffusion in nanocrystalline metalsand alloys-A status report [J]. Advanced Engineering Materials,2003,5:365-372.
[263] SHEN X, XU Z, LIAN J,JIANG Q. The deformation and fracture behavior of anelectrodeposited nanocrystalline Ni under compression [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2011,528:7878-7886.
[264] REDDY K M, GUO J, SHINODA Y, FUJITA T, HIRATA A, SINGH J, MCCAULEYJ,CHEN M. Enhanced mechanical properties of nanocrystalline boron carbide bynanoporosity and interface phases [J]. Nature communications,2012,3:1052.
[265] LI H Q,EBRAHIMI F. Transition of deformation and fracture behaviors innanostructured face-centered-cubic metals [J]. Applied Physics Letters,2004,84:4307-4309.
[266] HANLON T, KWON Y N,SURESH S. Grain size effects on the fatigue response ofnanocrystalline metals [J]. Scripta Materialia,2003,49:675-680.
[267] YANG Y, IMASOGIE B, FAN G, LIAW P K,SOBOYEJO W. Fatigue and fracture of abulk nanocrystalline NiFe alloy [J]. Metallurgical and Materials Transactions A,2008,39:1145-1156.
[268] TABACHNIKOVA E, PODOLSKIY A, BENGUS V, SMIRNOV S, LI H, LIAW P,CHOO H, CSACH K,MISKUF J. Strain-Rate Sensitivity and Failure Peculiarities inCompression of the Nanocrystalline Ni-20Pct Fe Alloy at Low Temperatures [J].Metallurgical and Materials Transactions A,2010,41:848-853.
[269] SCHUH C A, NIEH T G,IWASAKI H. The effect of solid solution W additions on themechanical properties of nanocrystalline Ni [J]. Acta Materialia,2003,51:431-443.
[270] XIAO C H, MIRSHAMS R A, WHANG S H,YIN W M. Tensile behavior and fracturein nickel and carbon doped nanocrystalline nickel [J]. Materials Science and Engineeringa-Structural Materials Properties Microstructure and Processing,2001,301:35-43.
[271] ASARO R, KRYSL P,KAD B. Deformation mechanism transitions in nanoscale FCCmetals [J]. Philosophical Magazine Letters,2003,83:733-743.
[272] OVID'KO I A,SHEINERMAN A G. Grain size effect on crack blunting innanocrystalline materials [J]. Scripta Materialia,2009,60:627-630.
[273] OVID'KO I A,SHEINERMAN A G. Triple junction nanocracks in deformednanocrystalline materials [J]. Acta Materialia,2004,52:1201-1209.
[274] ZHANG X Y, WU X L, LIU Q, ZUO R L, ZHU A W, JIANG P,WEI Q M. Phasetransformation accommodated plasticity in nanocrystalline nickel [J]. Applied PhysicsLetters,2008,93:
[275] R SNER H, BOUCHARAT N, MARKMANN J, PADMANABHAN K,WILDE G. Insitu transmission electron microscopic observations of deformation and fracture processes innanocrystalline palladium and Pd90Au10[J]. Materials Science and Engineering: A,2009,525:102-106.
[276] ZHANG Z, ECKERT J,SCHULTZ L. Difference in compressive and tensile fracturemechanisms of Zr59Cu20Al10Ni8Ti3bulk metallic glass [J]. Acta Materialia,2003,51:1167-1179.
[277] WANG Y, LI J, HAMZA A V,BARBEE T W. Ductile crystalline–amorphousnanolaminates [J]. Proceedings of the National Academy of Sciences,2007,104:11155-11160.
[2] SIEGEL R W. Nanostructured materials-mind over matter [J]. Nanostructured Materials,1994,4:121-138.
[3] GLEITER H. Nanostructured materials: Basic concepts and microstructure [J]. ActaMaterialia,2000,48:1-29.
[4] TJONG S C,CHEN H. Nanocrystalline materials and coatings [J]. Materials Science&Engineering R-Reports,2004,45:1-88.
[5] X. ZHU, R. BIRRINGER, U. HERR,H. GLEITER. X-ray diffraction studies of thestructure of nanometer-sized crystalline materials [J]. Physical Review B,1989,35:9085-9090.
[6] HERR U, JING J, BIRRINGER R, GONSER U,GLEITER H. Investigation ofnanocrystalline iron materials by M[o-umlaut]ssbauer spectroscopy [J]. Applied PhysicsLetters,1987,50:472-474.
[7] VAN SWYGENHOVEN H, CARO A,FARKAS D. Grain boundary structure and itsinfluence on plastic deformation of polycrystalline FCC metals at the nanoscale: A moleculardynamics study [J]. Scripta Materialia,2001,44:1513-1516.
[8] KUMAR K S, VAN SWYGENHOVEN H,SURESH S. Mechanical behavior ofnanocrystalline metals and alloys [J]. Acta Materialia,2003,51:5743-5774.
[9] THOMAS G J, SIEGEL R W,EASTMAN J A. Grain boundaries in nanophase palladium:High resolution electron microscopy and image simulation [J]. Scripta Metallurgica etMaterialia,1990,24:201-206.
[10] BIRRINGER R, GLEITER H, KLEIN H P,MARQUARDT P. Nanocrystalline materialsan approach to a novel solid structure with gas-like disorder?[J]. Physics Letters A,1984,102:365-369.
[11] SANDERS P G, FOUGERE G E, THOMPSON L J, EASTMAN J A,WEERTMAN J R.Improvements in the synthesis and compaction of nanocystalline materials [J].Nanostructured Materials,1997,8:243-252.
[12] SANDERS P G, EASTMAN J A,WEERTMAN J R. Elastic and tensile behavior ofnanocrystalline copper and palladium [J]. Acta Materialia,1997,45:4019-4025.
[13] SURYANARAYANA C. Mechanical alloying and milling [J]. Progress in MaterialsScience,2001,46:1-184.
[14] KOCH C C,WHITTENBERGER J D. Mechanical milling/alloying of intermetallics [J].Intermetallics,1996,4:339-355.
[15] KOCH C C. Synthesis of nanostructured materials by mechanical milling: problems andopportunities [J]. Nanostructured Materials,1997,9:13-22.
[16] PARK Y S, CHUNG K H, KIM N J,LAVERNIA E J. Microstructural investigation ofnanocrystalline bulk Al-Mg alloy fabricated by cryomilling and extrusion [J]. MaterialsScience and Engineering a-Structural Materials Properties Microstructure and Processing,2004,374:211-216.
[17] HUANG J Y, LIAO X Z, ZHU Y T, ZHOU F,LAVERNIA E J. Grain boundary structureof nanocrystalline Cu processed by cryomilling [J]. Philosophical Magazine,2003,83:1407-1419.
[18] HUANG B, JIANG H G, PEREZ R J, NUTT S R,LAVERNIA E J. The effect of Ni onthe cryogenic attritor milling of Metglas Fe78B13Si9[J]. Nanostructured Materials,1999,11:1009-1016.
[19] LU K. Nanocrystalline metals crystallized from amorphous solids: nanocrystallization,structure, and properties [J]. Materials Science and Engineering: R: Reports,1996,16:161-221.
[20] LU K, WEI W D,WANG J T. Microhardness and fracture properties of nanocrystallineNi---P alloy [J]. Scripta Metallurgica et Materialia,1990,24:2319-2323.
[21] LU K, WANG J T,WEI W D. A new method for synthesizing nanocrystalline alloys [J].Journal of Applied Physics,1991,69:522-524.
[22] NICOLAUS M M, SINNING H R,HAESSNER F. Crystallization behaviour andgeneration of a nanocrystalline state from amorphous Co33Zr67[J]. Materials Science andEngineering A,1992,150:101-112.
[23] AIHARA T AE A K, EL-ESKANDARANY M, HABAZAKI H, HASHIMOTO K, ETAL. IN: INOUE A, HASHIMOTO K, EDITORS. AMORPHOUS ANDNANOCRYSTALLINE MATERIALS;2000. P.103.[J].
[24] VALIEV R. Nanostructuring of metals by severe plastic deformation for advancedproperties [J]. Nature Materials,2004,3:511-516.
[25] VALIEV R. Materials science-Nanomaterial advantage [J]. Nature,2002,419:887-+.
[26] VALIEV R Z. Recent developments of SPD processing for fabrication of bulknanostructured materials [Z]. In: Thermec'2003, Pts1-5--CHANDRA T, TORRALBA JM,SAKAI T, ed.^eds.: Pulisher,2003:237-244
[27] VALIEV R Z,ALEKSANDROV I V. New developments in the field of fabrication ofbulk nanostructured materials by severe plastic deformation [J]. Physics of Metals andMetallography,2002,94: S4-S10.
[28] VALIEV R Z,ALEXANDROV I V. Development of severe plastic deformationtechniques for the fabrication of bulk nanostructured materials [J]. Annales DeChimie-Science Des Materiaux,2002,27:3-14.
[29] VALIEV R Z, ALEXANDROV I V, ZHU Y T,LOWE T C. Paradox of strength andductility in metals processed by severe plastic deformation [J]. Journal of Materials Research,2002,17:5-8.
[30] VALIEV R Z, ESTRIN Y, HORITA Z, LANGDON T G, ZEHETBAUER M J,ZHU Y T.Producing bulk ultrafine-grained materials by severe plastic deformation [J]. Jom,2006,58:33-39.
[31] VALIEV R Z, ISLAMGALIEV R K,ALEXANDROV I V. Bulk nanostructuredmaterials from severe plastic deformation [J]. Progress in Materials Science,2000,45:103-189.
[32] VALIEV R Z, KORZNIKOV A V,ALEXANDROV I V. Nanomaterials produced bysevere plastic deformation: An introduction [J]. Annales De Chimie-Science Des Materiaux,2002,27:1-2.
[33] VALIEV R Z, SERGUEEVA A V,MUKHERJEE A K. The effect of annealing on tensiledeformation behavior of nanostructured SPD titanium [J]. Scripta Materialia,2003,49:669-674.
[34] WEI Q, JIAO T, RAMESH K T, MA E, KECSKES L J, MAGNESS L, DOWDING R,KAZYKHANOV V U,VALIEV R Z. Mechanical behavior and dynamic failure ofhigh-strength ultrafine grained tungsten under uniaxial compression [J]. Acta Materialia,2006,54:77-87.
[35] WU S D, WANG Z G, JIANG C B, LI G Y, ALEXANDROV I V,VALIEV R Z. Shearbands in cyclically deformed ultrafine grained copper processed by ECAP [J]. MaterialsScience and Engineering A,2004,387-389:560-564.
[36] ZHILYAEV A P, LEE S, NURISLAMOVA G V, VALIEV R Z,LANGDON T G.Microhardness and microstructural evolution in pure nickel during high-pressure torsion [J].Scripta Materialia,2001,44:2753-2758.
[37] ZHILYAEV A P, NURISLAMOVA G V, KIM B K, BARO M D, SZPUNAR JA,LANGDON T G. Experimental parameters influencing grain refinement andmicrostructural evolution during high-pressure torsion [J]. Acta Materialia,2003,51:753-765.
[38] WANG Y B, LIAO X Z, ZHAO Y H, LAVERNIA E J, RINGER S P, HORITA Z,LANGDON T G,ZHU Y T. The role of stacking faults and twin boundaries in grainrefinement of a Cu-Zn alloy processed by high-pressure torsion [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2010,527:4959-4966.
[39] IWAHASHI Y, WANG J,HORITA Z. Principle of equal-channel angular pressing for theprocessing of ultrafinegrained materials [J]. Scripta Materialia,1996,35:143-146.
[40] MCMAHON G,ERB U. Bulk amorphous and nanocrystalline Ni-P alloys byelectroplating [J]. Microstructural science,1989,17:447-457.
[41] EL-SHERIK A M, ERB U,PAGE J. Microstructural evolution in pulse plated nickelelectrodeposits [J]. Surface and Coatings Technology,1997,88:70-78.
[42] EL-SHERIK A M, ERB U, PALUMBO G,AUST K T. Deviations from hall-petchbehaviour in as-prepared nanocrystalline nickel [J]. Scripta Metallurgica et Materialia,1992,27:1185-1188.
[43] ERB U. Electrodeposited nanocrystals: Synthesis, properties and industrial applications[J]. Nanostructured Materials,1995,6:533-538.
[44] ERB U, PALUMBO G, SZPUNAR B,AUST K T. Electrodeposited vs. consolidatednanocrystals: differences and similarities [J]. Nanostructured Materials,1997,9:261-270.
[45] JEONG D H, ERB U, AUST K T,PALUMBO G. The relationship between hardness andabrasive wear resistance of electrodeposited nanocrystalline Ni-P coatings [J]. ScriptaMaterialia,2003,48:1067-1072.
[46] JEONG D H, GONZALEZ F, PALUMBO G, AUST K T,ERB U. The effect of grainsize on the wear properties of electrodeposited nanocrystalline nickel coatings [J]. ScriptaMaterialia,2001,44:493-499.
[47] KARIMPOOR A A, ERB U, AUST K T,PALUMBO G. High strength nanocrystallinecobalt with high tensile ductility [J]. Scripta Materialia,2003,49:651-656.
[48] KIM S H, AUST K T, ERB U, GONZALEZ F,PALUMBO G. A comparison of thecorrosion behaviour of polycrystalline and nanocrystalline cobalt [J]. Scripta Materialia,2003,48:1379-1384.
[49] PALUMBO G, GONZALEZ F, BRENNENSTUHL A M, ERB U, SHMAYDAW,LICHTENBERGER P C. In-situ nuclear steam generator repair using electrodepositednanocrystalline nickel [J]. Nanostructured Materials,1997,9:737-746.
[50] ROBERTSON A, ERB U,PALUMBO G. Practical applications for electrodepositednanocrystalline materials [J]. Nanostructured Materials,1999,12:1035-1040.
[51] BOCKRIS J O M, AND RAZUMNEY, G. A., FUNDAMETAL ASPECTS OFELECTROCRYSTALLIZATION, P.27, PLENUM PRESS, NY (1967).[J].
[52] HALL E O. The Deformation and Ageing of Mild Steel: III Discussion of Results [J].Proceedings of the Physical Society London B,1951,64:747-753.
[53] PETCH N J. The cleavage strength of polycrystals [J]. Journal of the Iron and SteelInstitute,1953,174:25-28.
[54] GRAY I G T, LOWE T C, CADY C M, VALIEV R Z,ALEKSANDROV I V. Influenceof strain rate&temperature on the mechanical response of ultrafine-grained Cu, Ni, andAl-4Cu-0.5Zr [J]. Nanostructured Materials,1997,9:477-480.
[55] CHEN J, LU L,LU K. Hardness and strain rate sensitivity of nanocrystalline Cu [J].Scripta Materialia,2006,54:1913-1918.
[56] YOUSSEF K M, SCATTERGOOD R O, MURTY K L,KOCH C C. Ultratoughnanocrystalline copper with a narrow grain size distribution [J]. Applied Physics Letters,2004,85:929-931.
[57] HAOUAOUI M, KARAMAN I, MAIER H J,HARTWIG K T. Microstructure evolutionand mechanical behavior of bulk copper obtained by consolidation of micro-andnanopowders using equal-channel angular extrusion [J]. Metallurgical and MaterialsTransactions a-Physical Metallurgy and Materials Science,2004,35A:2935-2949.
[58] IYER R S, FREY C A, SASTRY S M L, WALLER B E,BUHRO W E. Plasticdeformation of nanocrystalline Cu and Cu-0.2wt.%B [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,1999,264:210-214.
[59] JIANG H G, ZHU Y T, BUTT D P, ALEXANDROV I V,LOWE T C. Microstructuralevolution, microhardness and thermal stability of HPT-processed Cu [J]. Materials Scienceand Engineering a-Structural Materials Properties Microstructure and Processing,2000,290:128-138.
[60] AGNEW S R, ELLIOTT B R, YOUNGDAHL C J, HEMKER K J,WEERTMAN J R.Microstructure and mechanical behavior of nanocrystalline metals [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2000,285:391-396.
[61] VALIEV R Z, KOZLOV E V, IVANOV Y F, LIAN J, NAZAROV A A,BAUDELET B.Deformation behaviour of ultra-fine-grained copper [J]. Acta Metallurgica et Materialia,1994,42:2467-2475.
[62] LU L, SHEN Y F, CHEN X H, QIAN L H,LU K. Ultrahigh strength and high electricalconductivity in copper [J]. Science,2004,304:422-426.
[63] MEYERS M A, MISHRA A,BENSON D J. Mechanical properties of nanocrystallinematerials [J]. Progress in Materials Science,2006,51:427-556.
[64] MA E. Instabilities and ductility of nanocrystalline and ultrafine-grained metals [J].Scripta Materialia,2003,49:663-668.
[65] EBRAHIMI F, ZHAI Q,KONG D. Deformation and fracture of electrodeposited copper[J]. Scripta Materialia,1998,39:315-321.
[66] HAYASHI K,ETO H. Pressure-Sintering of iron, cobalt, nickel and copper ultrafinepowders and the crystal grain size and hardness of the compacts [J]. J. Jpn. Inst. Met.,1989,53:221-226.
[67] KNAPP J A,FOLLSTAEDT D M. Hall-Petch relationship in pulsed-laser depositednickel films [J]. Journal of Materials Research,2004,19:218-227.
[68] SCHUH C A, NIEH T G,YAMASAKI T. Hall-Petch breakdown manifested in abrasivewear resistance of nanocrystalline nickel [J]. Scripta Materialia,2002,46:735-740.
[69] SCHIOTZ J,JACOBSEN K W. A maximum in the strength of nanocrystalline copper [J].Science,2003,301:1357-1359.
[70] ARGON A S,YIP S. The strongest size [J]. Philosophical Magazine Letters,2006,86:713-720.
[71] PAN Y, ZHOU Z F, FU S-Y, NIE Y,SUN C Q. FACTORS CONTROLLING THESTRONGEST SIZES IN THE INVERSE HALL-PETCH RELATIONSHIP [J]. Nano,2008,3:175-185.
[72] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Deformation mechanism crossover and mechanical behaviour in nanocrystalline materials[J]. Philosophical Magazine Letters,2003,83:385-393.
[73] VAN VLIET K J, TSIKATA S,SURESH S. Model experiments for direct visualizationof grain boundary deformation in nanocrystalline metals [J]. Applied Physics Letters,2003,83:1441-1443.
[74] LU K, LU L,SURESH S. Strengthening Materials by Engineering Coherent InternalBoundaries at the Nanoscale [J]. Science,2009,324:349-352.
[75] DAO M, LU L, SHEN Y F,SURESH S. Strength, strain-rate sensitivity and ductility ofcopper with nanoscale twins [J]. Acta Materialia,2006,54:5421-5432.
[76] LU L, SCHWAIGER R, SHAN Z W, DAO M, LU K,SURESH S. Nano-sized twinsinduce high rate sensitivity of flow stress in pure copper [J]. Acta Materialia,2005,53:2169-2179.
[77] SHEN Y F, LU L, DAO M,SURESH S. Strain rate sensitivity of Cu with nanoscaletwins [J]. Scripta Materialia,2006,55:319-322.
[78] SHEN Y F, LU L, LU Q H, JIN Z H,LU K. Tensile properties of copper with nano-scaletwins [J]. Scripta Materialia,2005,52:989-994.
[79] KOCH C C. Optimization of strength and ductility in nanocrystalline and ultrafinegrained metals [J]. Scripta Materialia,2003,49:657-662.
[80] KOCH C C, MORRIS D G, LU K,INOUE A. Ductility of nanostructured materials [J].Mrs Bulletin,1999,24:54-58.
[81] KOCH C C, YOUSSEF K M, SCATTERGOOD R O,MURTY K L. Breakthroughs inOptimization of Mechanical Properties of Nanostructured Metals and Alloys [J]. AdvancedEngineering Materials,2005,7:787-794.
[82] WANG Y M, WANG K, PAN D, LU K, HEMKER K J,MA E. Microsample tensiletesting of nanocrystalline copper [J]. Scripta Materialia,2003,48:1581-1586.
[83] NIEMAN G W, WEERTMAN J R,SIEGEL R W. Mechanical behavior ofnanocrystalline Cu and Pd [J]. Journal of Materials Research,1991,6:1012-1027.
[84] LEGROS M, ELLIOTT B R, RITTNER M N, WEERTMAN J R,HEMKER K J.Microsample tensile testing of nanocrystalline metals [J]. Philosophical Magazine a-Physicsof Condensed Matter Structure Defects and Mechanical Properties,2000,80:1017-1026.
[85] WU X J, DU L G, ZHANG H F, LIU J F, ZHOU Y S, LI Z Q, XIONG L Y,BAI Y L.Synthesis and tensile property of nanocrystalline metal copper [J]. Nanostructured Materials,1999,12:221-224.
[86] CHENG S, MA E, WANG Y M, KECSKES L J, YOUSSEF K M, KOCH C C,TROCIEWITZ U P,HAN K. Tensile properties of in situ consolidated nanocrystalline Cu [J].Acta Materialia,2005,53:1521-1533.
[87] WANG Y M,MA E. Temperature and strain rate effects on the strength and ductility ofnanostructured copper [J]. Applied Physics Letters,2003,83:3165-3167.
[88] CONRAD H,NARAYAN J. Mechanisms for grain size hardening and softening in Zn[J]. Acta Materialia,2002,50:5067-5078.
[89] YOUSSEF K M, SCATTERGOOD R O, MURTY K L, HORTON J A,KOCH C C.Ultrahigh strength and high ductility of bulk nanocrystalline copper [J]. Applied PhysicsLetters,2005,87:
[90] SCHWAIGER R, MOSER B, DAO M, CHOLLACOOP N,SURESH S. Some criticalexperiments on the strain-rate sensitivity of nanocrystalline nickel [J]. Acta Materialia,2003,51:5159-5172.
[91] DALLA TORRE F, VAN SWYGENHOVEN H,VICTORIA M. Nanocrystallineelectrodeposited Ni: microstructure and tensile properties [J]. Acta Materialia,2002,50:3957-3970.
[92] WEERTMAN J R, FARKAS D, HEMKER K, KUNG H, MAYO M, MITRA R,VANSWYGENHOVEN H. Structure and mechanical behavior of bulk nanocrystalline materials[J]. Mrs Bulletin,1999,24:44-50.
[93] LI H,EBRAHIMI F. Transition of deformation and fracture behaviors in nanostructuredface-centered-cubic metals [J]. Applied Physics Letters,2004,84:4307-4309.
[94] WANG L, HAN X, LIU P, YUE Y, ZHANG Z,MA E. In Situ Observation ofDislocation Behavior in Nanometer Grains [J]. Physical Review Letters,2010,105:
[95] WU X L, ZHU Y T, WEI Y G,WEI Q. Strong Strain Hardening in NanocrystallineNickel [J]. Physical Review Letters,2009,103:
[96] WANG Y, CHEN M, ZHOU F,MA E. High tensile ductility in a nanostructured metal[J]. Nature,2002,419:912-915.
[97] GIANOLA D S, VAN PETEGEM S, LEGROS M, BRANDSTETTER S, VANSWYGENHOVEN H,HEMKER K J. Stress-assisted discontinuous grain growth and itseffect on the deformation behavior of nanocrystalline aluminum thin films [J]. ActaMaterialia,2006,54:2253-2263.
[98] GU C, LIAN J, JIANG Z,JIANG Q. Enhanced tensile ductility in an electrodepositednanocrystalline Ni [J]. Scripta Materialia,2006,54:579-584.
[99] LU L, CHEN X, HUANG X,LU K. Revealing the Maximum Strength in NanotwinnedCopper [J]. Science,2009,323:607-610.
[100] LI H Q,EBRAHIMI F. Ductile-to-brittle transition in nanocrystalline metals [J].Advanced Materials,2005,17:1969-1971.
[101] HUGO R C, KUNG H, WEERTMAN J R, MITRA R, KNAPP J A,FOLLSTAEDT DM. In-situ TEM tensile testing of DC magnetron sputtered and pulsed laser deposited Ni thinfilms [J]. Acta Materialia,2003,51:1937-1943.
[102] HASNAOUI A, VAN SWYGENHOVEN H,DERLET P M. Dimples onnanocrystalline fracture surfaces as evidence for shear plane formation [J]. Science,2003,300:1550-1552.
[103] SHAN Z, KNAPP J A, FOLLSTAEDT D M, STACH E A, WIEZOREK J M K,MAOS X. Inter-and intra-agglomerate fracture in nanocrystalline nickel [J]. Physical ReviewLetters,2008,100:
[104] KUMAR K S, SURESH S, CHISHOLM M F, HORTON J A,WANG P. Deformationof electrodeposited nanocrystalline nickel [J]. Acta Materialia,2003,51:387-405.
[105] DALLA TORRE F, SPATIG P, SCHAUBLIN R,VICTORIA M. Deformationbehaviour and microstructure of nanocrystalline electrodeposited and high pressure torsionednickel [J]. Acta Materialia,2005,53:2337-2349.
[106] WANG Y M, HAMZA A V,MA E. Temperature-dependent strain rate sensitivity andactivation volume of nanocrystalline Ni [J]. Acta Materialia,2006,54:2715-2726.
[107] WANG Y M, HAMZA A V,MA E. Activation volume and density of mobiledislocations in plastically deforming nanocrystalline Ni [J]. Applied Physics Letters,2005,86:241917-3.
[108] WEI Q, CHENG S, RAMESH K T,MA E. Effect of nanocrystalline and ultrafine grainsizes on the strain rate sensitivity and activation volume: fcc versus bcc metals [J]. MaterialsScience and Engineering a-Structural Materials Properties Microstructure and Processing,2004,381:71-79.
[109] LU L, LI S X,LU K. An abnormal strain rate effect on tensile behavior innanocrystalline copper [J]. Scripta Materialia,2001,45:1163-1169.
[110] CARREKER JR R P,HIBBARD JR W R. Tensile deformation of high-purity copper asa function of temperature, strain rate, and grain size [J]. Acta Metallurgica,1953,1:654-663.
[111] ZEHETBAUER M,SEUMER V. Cold work hardening in stages IV and V of F.C.C.metals—I. Experiments and interpretation [J]. Acta Metallurgica et Materialia,1993,41:577-588.
[112] BOCHNIAK W. Mode of deformation and the Cottrell-Strokes law in F.C.C. singlecrystals [J]. Acta Metallurgica et Materialia,1995,43:225-233.
[113] DAO M, LU L, ASARO R J, DE HOSSON J T M,MA E. Toward a quantitativeunderstanding of mechanical behavior of nanocrystalline metals [J]. Acta Materialia,2007,55:4041-4065.
[114] LU L, DAO M, ZHU T,LI J. Size dependence of rate-controlling deformationmechanisms in nanotwinned copper [J]. Scripta Materialia,2009,60:1062-1066.
[115] CHENG S, SPENCER J A,MILLIGAN W W. Strength and tension/compressionasymmetry in nanostructured and ultrafine-grain metals [J]. Acta Materialia,2003,51:4505-4518.
[116] ASARO R J,SURESH S. Mechanistic models for the activation volume and ratesensitivity in metals with nanocrystalline grains and nano-scale twins [J]. Acta Materialia,2005,53:3369-3382.
[117] VAN SWYGENHOVEN H, DERLET P M,FROSETH A G. Nucleation andpropagation of dislocations in nanocrystalline fcc metals [J]. Acta Materialia,2006,54:1975-1983.
[118] MA E. Eight routes to improve the tensile ductility of bulk nanostructured metals andalloys [J]. Jom,2006,58:49-53.
[119] WANG Y M,MA E. Three strategies to achieve uniform tensile deformation in ananostructured metal [J]. Acta Materialia,2004,52:1699-1709.
[120] DERLET P M, HASNAOUI A,VAN SWYGENHOVEN H. Atomistic simulations asguidance to experiments [J]. Scripta Materialia,2003,49:629-635.
[121] VAN SWYGENHOVEN H. Polycrystalline materials-Grain boundaries anddislocations [J]. Science,2002,296:66-67.
[122] VAN SWYGENHOVEN H, SPACZER M,CARO A. Microscopic description ofplasticity in computer generated metallic nanophase samples: A comparison between Cu andNi [J]. Acta Materialia,1999,47:3117-3126.
[123] SCHIOTZ J, VEGGE T, DI TOLLA F D,JACOBSEN K W. Atomic-scale simulationsof the mechanical deformation of nanocrystalline metals [J]. Physical Review B,1999,60:11971-11983.
[124] SCHI TZ J, DI TOLLA F D,JACOBSEN K W. Softening of nanocrystalline metals atvery small grain sizes [J]. Nature,1998,391:561-563.
[125] WOLF D, YAMAKOV V, PHILLPOT S R, MUKHERJEE A,GLEITER H.Deformation of nanocrystalline materials by molecular-dynamics simulation: relationship toexperiments?[J]. Acta Materialia,2005,53:1-40.
[126] YAMAKOV V, WOLF D, PHILLPOT S R,GLEITER H. Deformation twinning innanocrystalline Al by molecular dynamics simulation [J]. Acta Materialia,2002,50:5005-5020.
[127] YAMAKOV V, WOLF D, PHILLPOT S R,GLEITER H. Dislocation-dislocation anddislocation-twin reactions in nanocrystalline Al by molecular dynamics simulation [J]. ActaMaterialia,2003,51:4135-4147.
[128] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Deformation-mechanism map for nanocrystalline metals by molecular-dynamics simulation[J]. Nature Materials,2004,3:43-47.
[129] VAN SWYGENHOVEN H, DERLET P M,FROSETH A G. Stacking fault energiesand slip in nanocrystalline metals [J]. Nature Materials,2004,3:399-403.
[130] FARKAS D, VAN PETEGEM S, DERLET P M,VAN SWYGENHOVEN H.Dislocation activity and nano-void formation near crack tips in nanocrystalline Ni [J]. ActaMaterialia,2005,53:3115-3123.
[131] FARKAS D, VAN SWYGENHOVEN H,DERLET P M. Intergranular fracture innanocrystalline metals [J]. Physical Review B,2002,66:
[132] CAO A,WEI Y. Atomistic simulations of crack nucleation and intergranular fracture inbulk nanocrystalline nickel [J]. Physical Review B,2007,76:
[133] FARKAS D, WILLEMANN M,HYDE B. Atomistic mechanisms of fatigue innanocrystalline metals [J]. Physical Review Letters,2005,94:
[134] DAVILA L P, ERHART P, BRINGA E M, MEYERS M A, LUBARDA V A,SCHNEIDER M S, BECKER R,KUMAR M. Atomistic modeling of shock-induced voidcollapse in copper [J]. Applied Physics Letters,2005,86:
[135] LUBARDA V A, SCHNEIDER M S, KALANTAR D H, REMINGTON BA,MEYERS M A. Void growth by dislocation emission [J]. Acta Materialia,2004,52:1397-1408.
[136] MEYERS M A, TRAIVIRATANA S, LUBARDA V A, BENSON D J,BRINGA E M.The role of dislocations in the growth of nanosized voids in ductile failure of metals [J]. Jom,2009,61:35-41.
[137] TRAIVIRATANA S, BRINGA E M, BENSON D J,MEYERS M A. Void growth inmetals: Atomistic calculations [J]. Acta Materialia,2008,56:3874-3886.
[138] VAN SWYGENHOVEN H,DERLET P A. Grain-boundary sliding in nanocrystallinefcc metals [J]. Physical Review B,2001,64:
[139] SERGUEEVA A V, MARA N A, KRASILNIKOV N A, VALIEV R Z,MUKHERJEE AK. Cooperative grain boundary sliding in nanocrystalline materials [J]. PhilosophicalMagazine,2006,86:5797-5804.
[140] IVANISENKO Y, KURMANAEVA L, WEISSMUELLER J, YANG K, MARKMANNJ, ROESNER H, SCHERER T,FECHT H J. Deformation mechanisms in nanocrystallinepalladium at large strains [J]. Acta Materialia,2009,57:3391-3401.
[141] CHINH N Q, SZOMMER P, HORITA Z,LANGDON T G. Experimental evidence forgrain-boundary sliding in ultrafine-grained aluminum processed by severe plasticdeformation [J]. Advanced Materials,2006,18:34-39.
[142] BOBYLEV S V,OVID'KO I A. Nanograin nucleation initiated by intergrain slidingand/or lattice slip in nanomaterials [J]. Applied Physics Letters,2008,92:
[143] OVID'KO I A,SHEINERMAN A G. Enhanced ductility of nanomaterials throughoptimization of grain boundary sliding and diffusion processes [J]. Acta Materialia,2009,57:2217-2228.
[144] KE M, HACKNEY S A, MILLIGAN W W,AIFANTIS E C. Observation andmeasurement of grain rotation and plastic strain in nanostructured metal thin films [J].Nanostructured Materials,1995,5:689-697.
[145] SHAN Z, STACH E A, WIEZOREK J M K, KNAPP J A, FOLLSTAEDT D M,MAOS X. Grain Boundary-Mediated Plasticity in Nanocrystalline Nickel [J]. Science,2004,305:654-657.
[146] JIN M, MINOR A M, STACH E A,MORRIS J W. Direct observation ofdeformation-induced grain growth during the nanoindentation of ultrafine-grained Al atroom temperature [J]. Acta Materialia,2004,52:5381-5387.
[147] WANG Y B, LI B Q, SUI M L,MAO S X. Deformation-induced grain rotation andgrowth in nanocrystalline Ni [J]. Applied Physics Letters,2008,92:
[148] LIAO X Z, KILMAMETOV A R, VALIEV R Z, GAO H S, LI X D, MUKHERJEE AK, BINGERT J F,ZHU Y T. High-pressure torsion-induced grain growth in electrodepositednanocrystalline Ni [J]. Applied Physics Letters,2006,88:
[149] WANG Y B, HO J C, CAO Y, LIAO X Z, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P,ZHU Y T. Dislocation density evolution during high pressure torsion of ananocrystalline Ni-Fe alloy [J]. Applied Physics Letters,2009,94:
[150] NI S, WANG Y B, LIAO X Z, ALHAJERI S N, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P, LANGDON T G,ZHU Y T. Grain growth and dislocation density evolution ina nanocrystalline Ni-Fe alloy induced by high-pressure torsion [J]. Scripta Materialia,2011,64:327-330.
[151] SHAN Z W, WIEZOREK J M K, STACH E A, FOLLSTAEDT D M, KNAPP JA,MAO S X. Dislocation dynamics in nanocrystalline nickel [J]. Physical Review Letters,2007,98:
[152] WANG Y M, OTT R T, HAMZA A V, BESSER M F, ALMER J,KRAMER M J.Achieving Large Uniform Tensile Ductility in Nanocrystalline Metals [J]. Physical ReviewLetters,2010,105:
[153] BUDROVIC Z, VAN SWYGENHOVEN H, DERLET P M, VAN PETEGEMS,SCHMITT B. Plastic deformation with reversible peak broadening in nanocrystallinenickel [J]. Science,2004,304:273-276.
[154] WU X, MA E,ZHU Y T. Deformation defects in nanocrystalline nickel [J]. Journal ofMaterials Science,2007,42:1427-1432.
[155] WU X-L,MA E. Dislocations in nanocrystalline grains [J]. Applied Physics Letters,2006,88:
[156] ZHU Y T, LIAO X Z,WU X L. Deformation twinning in bulk nanocrystalline metals:Experimental observations [J]. Jom,2008,60:60-64.
[157] CHEN M, MA E, HEMKER K J, SHENG H, WANG Y,CHENG X. DeformationTwinning in Nanocrystalline Aluminum [J]. Science,2003,300:1275-1277.
[158] HE J H, CHUNG K H, LIAO X Z, ZHU Y T,LAVERNIA E J. Mechanicalmilling-induced deformation twinning in Fcc materials with high stacking fault energy [J].Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,2003,34:707-712.
[159] LIAO X Z, ZHAO Y H, SRINIVASAN S G, ZHU Y T, VALIEV R Z,GUNDEROV DV. Deformation twinning in nanocrystalline copper at room temperature and low strain rate[J]. Applied Physics Letters,2004,84:592-594.
[160] LIAO X Z, ZHOU F, LAVERNIA E J, SRINIVASAN S G, BASKES M I, HE DW,ZHU Y T. Deformation mechanism in nanocrystalline Al: Partial dislocation slip [J].Applied Physics Letters,2003,83:632-634.
[161] ROSNER H, MARKMANN J,WEISSMULLER J. Deformation twinning innanocrystalline Pd [J]. Philosophical Magazine Letters,2004,84:321-334.
[162] ZHU Y T,LANGDON T G. Influence of grain size on deformation mechanisms: Anextension to nanocrystalline materials [J]. Materials Science and Engineering a-StructuralMaterials Properties Microstructure and Processing,2005,409:234-242.
[163] TRIMBY P W. Orientation mapping of nanostructured materials using transmissionKikuchi diffraction in the scanning electron microscope [J]. Ultramicroscopy,2012,120:16-24.
[164] TRIMBY P W, CAO Y, CHEN Z, HAN S, HEMKER K J, LIAN J, LIAO X,ROTTMANN P, SAMUDRALA S, SUN J, WANG J T, WHEELER J,CAIRNEY J M.Characterizing deformed ultrafine-grained and nanocrystalline materials using transmissionKikuchi diffraction in a scanning electron microscope [J]. Acta Materialia,2014,62:69-80.
[165] WU X, ZHU Y T, CHEN M W,MA E. Twinning and stacking fault formation duringtensile deformation of nanocrystalline Ni [J]. Scripta Materialia,2006,54:1685-1690.
[166] MA E. Watching the nanograins roll [J]. Science,2004,305:623-624.
[167] ZHU Y T,LIAO X Z. Nanostructured metals-Retaining ductility [J]. Nature Materials,2004,3:351-352.
[168] WANG Y B, HO J C, LIAO X Z, LI H Q, RINGER S P,ZHU Y T. Mechanism of graingrowth during severe plastic deformation of a nanocrystalline Ni-Fe alloy [J]. AppliedPhysics Letters,2009,94:
[169] SANSOZ F,DUPONT V. Grain growth behavior at absolute zero duringnanocrystalline metal indentation [J]. Applied Physics Letters,2006,89:
[170] JIANG Z H, LIU X L, LI G Y, JIANG Q,LIAN J S. Strain rate sensitivity of ananocrystalline Cu synthesized by electric brush plating [J]. Applied Physics Letters,2006,88:
[171] CHEN M W, MA E, HEMKER K J, SHENG H W, WANG Y M,CHENG X M.Deformation twinning in nanocrystalline aluminum [J]. Science,2003,300:1275-1277.
[172] VAN SWYGENHOVEN H, DERLET P M,HASNAOUI A. Atomic mechanism fordislocation emission from nanosized grain boundaries [J]. Physical Review B,2002,66:
[173] VAN SWYGENHOVEN H,WEERTMAN J R. Deformation in nanocrystalline metals[J]. Materials Today,2006,9:24-31.
[174] NI S, WANG Y B, LIAO X Z, FIGUEIREDO R B, LI H Q, ZHAO Y H, LAVERNIAE J, RINGER S P, LANGDON T G,ZHU Y T. Strain softening in nanocrystalline Ni-Fe alloyinduced by large HPT revolutions [J]. Materials Science and Engineering a-StructuralMaterials Properties Microstructure and Processing,2011,528:4807-4811.
[175] NI S, WANG Y B, LIAO X Z, ALHAJERI S N, LI H Q, ZHAO Y H, LAVERNIA E J,RINGER S P, LANGDON T G,ZHU Y T. Strain hardening and softening in a nanocrystallineNi-Fe alloy induced by severe plastic deformation [J]. Materials Science and Engineeringa-Structural Materials Properties Microstructure and Processing,2011,528:3398-3403.
[176] PAN D, KUWANO S, FUJITA T,CHEN M. Ultra-large room-temperature compressiveplasticity of a nanocrystalline metal [J]. Nano Letters,2007,7:2108-2111.
[177] CHENG S, ZHAO Y, GUO Y, LI Y, WEI Q, WANG X L, REN Y, LIAW P K, CHOOH,LAVERNIA E J. High Plasticity and Substantial Deformation in Nanocrystalline NiFeAlloys Under Dynamic Loading [J]. Advanced Materials,2009,21:5001-5004.
[178] WANG Y M,MA E. On the origin of ultrahigh cryogenic strength of nanocrystallinemetals [J]. Applied Physics Letters,2004,85:2750-2752.
[179] WEI Q, CHENG S, RAMESH K T,MA E. Effect of nanocrystalline and ultrafine grainsizes on the strain rate sensitivity and activation volume: fcc versus bcc metals [J]. MaterialsScience and Engineering A,2004,381:71-79.
[180] HIRTH J P,LOTHE J. Theroy of dislcoations [J]. Wiley, New York,2nd edn.,1982: pp.159,752.
[181] GU C, LIAN J,JIANG Q. Layered nanostructured Ni with modulated hardnessfabricated by surfactant-assistant electrodeposition [J]. Scripta Materialia,2007,57:233-236.
[182] GU C, LIAN J,JIANG Z. High Strength Nanocrystalline Ni-Co Alloy with EnhancedTensile Ductility [J]. Advanced Engineering Materials,2006,8:252-256.
[183] WANG Y,MA E. On the origin of ultrahigh cryogenic strength of nanocrystallinemetals [J]. Applied Physics Letters,2004,85:2750-2752.
[184] LIAO X Z, ZHOU F, LAVERNIA E J, HE D W,ZHU Y T. Deformation twins innanocrystalline Al [J]. Applied Physics Letters,2003,83:5062-5064.
[185] ZHU Y T, LIAO X Z, SRINIVASAN S G, ZHAO Y H, BASKES M I, ZHOUF,LAVERNIA E J. Nucleation and growth of deformation twins in nanocrystalline aluminum[J]. Applied Physics Letters,2004,85:5049-5051.
[186] ZHU Y T, NARAYAN J, HIRTH J P, MAHAJAN S, WU X L,LIAO X Z. Formation ofsingle and multiple deformation twins in nanocrystalline fcc metals [J]. Acta Materialia,2009,57:3763-3770.
[187] LIAO X Z, HUANG J Y, ZHU Y T, ZHOU F,LAVERNIA E J. Nanostructures anddeformation mechanisms in a cryogenically ball-milled Al-Mg alloy [J]. PhilosophicalMagazine,2003,83:3065-3075.
[188] VAN SWYGENHOVEN H, DERLET P M,FR SETH A G. Stacking fault energies andslip in nanocrystalline metals [J]. Nature Materials,01Jun2004,3:399-403.
[189] YAMAKOV V, WOLF D, PHILLPOT S R, MUKHERJEE A K,GLEITER H.Dislocation processes in the deformation of nanocrystalline aluminium bymolecular-dynamics simulation [J]. Nature Materials,2002,1:45-48.
[190] WANG Z W, WANG Y B, LIAO X Z, ZHAO Y H, LAVERNIA E J, ZHU Y T,HORITA Z,LANGDON T G. Influence of stacking fault energy on deformation mechanismand dislocation storage capacity in ultrafine-grained materials [J]. Scripta Materialia,2009,60:52-55.
[191] NI S, WANG Y B, LIAO X Z, FIGUEIREDO R B, LI H Q, RINGER S P, LANGDONT G,ZHU Y T. The effect of dislocation density on the interactions between dislocations andtwin boundaries in nanocrystalline materials [J]. Acta Materialia,2012,60:3181-3189.
[192] VALIEV R, GERTSMAN V Y,KAIBYSHEV O. Grain boundary structure andproperties under external influences [J]. Physica status solidi (a),1986,97:11-56.
[193] ZHU Y T, HUANG J Y, GUBICZA J, UNGAR T, WANG Y M, MA E,VALIEV R Z.Nanostructures in Ti processed by severe plastic deformation [J]. Journal of MaterialsResearch,2003,18:1908-1917.
[194] VALIEV R, MISHRAL R, GROZAL J,MUKHERJEE A. Processing of nanostructurednickel by severe plastic deformation consolidation of ball-milled powder [J]. Scriptamaterialia,1996,34:1443-1448.
[195] MISHIN O, GERTSMAN V Y, VALIEV R,GOTTSTEIN G. Grain boundarydistribution and texture in ultrafine-grained copper produced by severe plastic deformation[J]. Scripta Materialia,1996,35:873-878.
[196] FEDOROV A A, GUTKIN M Y,OVID'KO I A. Transformations of grain boundarydislocation pile-ups in nano-and polycrystalline materials [J]. Acta Materialia,2003,51:887-898.
[197] HUANG J Y, ZHU Y T, JIANG H,LOWE T C. Microstructures and dislocationconfigurations in nanostructured Cu processed by repetitive corrugation and straightening [J].Acta Materialia,2001,49:1497-1505.
[198] WU X L,ZHU Y T. Partial-dislocation-mediated processes in nanocrystalline Ni withnonequilibrium grain boundaries [J]. Applied Physics Letters,2006,89:
[199] LIAN J S, GU C D, JIANG Q,JIANG Z H. Strain rate sensitivity offace-centered-cubic nanocrystalline materials based on dislocation deformation [J]. Journalof Applied Physics,2006,99:
[200] GUTKIN M Y, OVID'KO I A,SKIBA N V. Crossover from grain boundary sliding torotational deformation in nanocrystalline materials [J]. Acta Materialia,2003,51:4059-4071.
[201] KLEMENT W, WILLENS R,DUWEZ P. Non-crystalline structure in solidifiedgold–silicon alloys [J].1960:
[202] HE Y, POON S,SHIFLET G. Synthesis and properties of metallic glasses that containaluminum [J]. Science,1988,241:1640-1642.
[203] JANG J,KOCH C. Amorphization and disordering of the Ni3Al ordered intermetallicby mechanical milling [J]. J. Mater. Res,1990,5:498-509.
[204] WINTERS R R,HAMMACK W S. Pressure-induced amorphization of R-Al5Li3Cu: astructural relation among amorphous metals, quasi-crystals, and curved space [J]. Science,1993,260:202-204.
[205] INOUE A. Stabilization of metallic supercooled liquid and bulk amorphous alloys [J].Acta Materialia,2000,48:279-306.
[206] HOFMANN D C, SUH J-Y, WIEST A, DUAN G, LIND M-L, DEMETRIOU MD,JOHNSON W L. Designing metallic glass matrix composites with high toughness andtensile ductility [J]. Nature,2008,451:1085-U3.
[207] WANG W-H, DONG C,SHEK C. Bulk metallic glasses [J]. Materials Science andEngineering: R: Reports,2004,44:45-89.
[208] GREER A L. Metallic glasses [J]. Science,1995,267:1947-1953.
[209] FECHT H. Defect-induced melting and solid-state amorphization [J]. Nature,1992,356:133-135.
[210] BHAT M H, MOLINERO V, SOIGNARD E, SOLOMON V C, SASTRY S, YARGERJ L,ANGELL C A. Vitrification of a monatomic metallic liquid [J]. Nature,2007,448:787-U3.
[211] HOLZ M, ZIEMANN P,BUCKEL W. Direct evidence for amorphization of puregallium by low-temperature ion irradiation [J]. Physical review letters,1983,51:1584.
[212] VO VAN H,ODAGAKI T. Glass Formation and Thermodynamics of SupercooledMonatomic Liquids [J]. Journal of Physical Chemistry B,2011,115:6946-6956.
[213] KUNDIG A A, LOFFLER J F, JOHNSON W L, UGGOWITZER PJ,THIYAGARAJAN P. Influence of decomposition on the thermal stability of undercooledZr-Ti-Cu-Ni-Al alloys [J]. Scripta Materialia,2001,44:1269-1273.
[214] IKEDA H, QI Y, CAGIN T, SAMWER K, JOHNSON W L,GODDARD W A. Strainrate induced amorphization in metallic nanowires [J]. Physical Review Letters,1999,82:2900-2903.
[215] SWAMY V, KUZNETSOV A, DUBROVINSKY L S, MCMILLAN P F,PRAKAPENKA V B, SHEN G,MUDDLE B C. Size-dependent pressure-inducedamorphization in nanoscale TiO2[J]. Physical review letters,2006,96:135702.
[216] MELDRUM A, BOATNER L A,EWING R C. Nanocrystalline zirconia can beamorphized by ion irradiation [J]. Physical Review Letters,2002,88:
[217] JOHANNESSEN B, KLUTH P, LLEWELLYN D, FORAN G J, COOKSOND,RIDGWAY M C. Amorphization of embedded Cu nanocrystals by ion irradiation [J].Applied physics letters,2007,90:073119.
[218] FECHT H. Thermodynamic Properties of Amorphous Solids--Glass Formation andGlass Transition--(Overview)[J]. Materials transactions-JIM,1995,36:777-777.
[219] MA E. Amorphization in mechanically driven material systems [J]. Scripta materialia,2003,49:941-946.
[220] CHEN M, MCCAULEY J W,HEMKER K J. Shock-Induced Localized Amorphizationin Boron Carbide [J]. Science,2003,299:1563-1566.
[221] COURTNEY T H. Mechanical behavior of materials [M]. Place Published: WavelandPress,2005.
[222] CHENG S, ZHAO Y, WANG Y, LI Y, WANG X-L, LIAW P K,LAVERNIA E J.Structure Modulation Driven by Cyclic Deformation in Nanocrystalline NiFe [J]. PhysicalReview Letters,2010,104:
[223] HUANG J Y, ZHU Y T, LIAO X Z,VALIEV R Z. Amorphization of TiNi induced byhigh-pressure torsion [J]. Philosophical Magazine Letters,2004,84:183-190.
[224] LIN Z, ZHUO M, SUN Z, VEYSSI RE P,ZHOU Y. Amorphization by dislocationaccumulation in shear bands [J]. Acta Materialia,2009,57:2851-2857.
[225] WU X, TAO N, HONG Y, LU J,LU K. Localized solid-state amorphization at grainboundaries in a nanocrystalline Al solid solution subjected to surface mechanical attrition [J].Journal of Physics D: Applied Physics,2005,38:4140.
[226] HUANG J, ZHU Y, LIAO X,VALIEV R. Amorphization of TiNi induced byhigh-pressure torsion [J]. Philosophical magazine letters,2004,84:183-190.
[227] SAGEL A, WANDERKA N, WUNDERLICH R, SCHUBERT-BISCHOFF P,FECHTH-J. Early stages of solid-state amorphization reaction during mechanical alloying of amulticomponent Zr-powder mixture [J]. Scripta materialia,1997,38:163-169.
[228] YAMADA K,KOCH C C. The influence of mill energy and temperature on thestructure of the TiNi intermetallic after mechanical attrition [J]. Journal of materials research,1993,8:1317-1326.
[229] HUANG J Y, YASUDA H,MORI H. Deformation-induced amorphization inball-milled silicon [J]. Philosophical Magazine Letters,1999,79:305-314.
[230] FAN G, GUO F, HU Z, QUAN M,LU K. Amorphization of selenium induced byhigh-energy ball milling [J]. Physical Review B,1997,55:11010.
[231] BENEDICTUS R, HAN K, TRAEHOLT C, B TTGER A,MITTEMEIJER E. Solidstate amorphization in Ni–Ti systems: the effect of structure on the kinetics of interface andgrain-boundary amorphization [J]. Acta materialia,1998,46:5491-5508.
[232] WU Y,XU Y. Lattice-distortion-induced amorphization in indented [110] silicon [J].Journal of materials research,1999,14:682-687.
[233] WU Y, YANG X,XU Y. Cross-sectional electron microscopy observation on theamorphized indentation region in [001] single-crystal silicon [J]. Acta materialia,1999,47:2431-2436.
[234] LI M. Defect-induced topological order-to-disorder transitions in two-dimensionalbinary substitutional solid solutions: A molecular dynamics study [J]. Physical Review B,2000,62:13979-13995.
[235] OVID'KO I A,REIZIS A B. Effect of elastic distortions on solid-state amorphization atgrain boundaries and dislocations [J]. Journal of Physics D-Applied Physics,1999,32:2833-2840.
[236] KINGMA K J, MEADE C, HEMLEY R J, MAO H-K,VEBLEN D R. Microstructuralobservations of alpha-quartz amorphization [J]. Science,1993,259:666-669.
[237] OVID’KO I. Review on the fracture processes in nanocrystalline materials [J]. Journalof materials science,2007,42:1694-1708.
[238] BRINGA E M, TRAIVIRATANA S,MEYERS M A. Void initiation in fcc metals:Effect of loading orientation and nanocrystalline effects [J]. Acta Materialia,2010,58:4458-4477.
[239] MYERS S, BIRNBAUM H, CORBETT J, DELEO G, ESTREICHER S, HALLER E,JENA P, JOHNSON N, KIRCHHEIM R,PEARTON S. Hydrogen interactions with defectsin crystalline solids [J]. Reviews of Modern Physics,1992,64:559-617.
[240] CUITINO A,ORTIZ M. Ductile fracture by vacancy condensation in fcc single crystals[J]. Acta materialia,1996,44:427-436.
[241] RICE J, JOHNSON M,KANNINEN M. Inelastic behavior of solids [J]. McGraw-Hill,New York,1970,641:
[242] AHN D, SOFRONIS P, KUMAR M, BELAK J,MINICH R. Void growth bydislocation-loop emission [J]. Journal of applied physics,2007,101:063514.
[243] SEPPALA E T, BELAK J,RUDD R E. Onset of void coalescence during dynamicfracture of ductile metals [J]. Physical Review Letters,2004,93:
[244] VORONO G. Nouvelles applications des paramètres continus à la théorie des formesquadratiques. Deuxième mémoire. Recherches sur les parallélloèdres primitifs [J]. Journalfür die reine und angewandte Mathematik,1908,134:198-287.
[245] DAW M S. Model of metallic cohesion: The embedded-atom method [J]. PhysicalReview B,1989,39:7441.
[246] RIBBE J, SCHMITZ G, R SNER H, LAPOVOK R, ESTRIN Y, WILDE G,DIVINSKIS V. Effect of back pressure during equal-channel angular pressing on deformation-inducedporosity in copper [J]. Scripta Materialia,2013,68:925-928.
[247] LAPOVOK R. Damage evolution under severe plastic deformation [J]. InternationalJournal of fracture,2002,115:159-172.
[248] ZHANG Z, ZHANG H, PAN X, DAS J,ECKERT J. Effect of aspect ratio on thecompressive deformation and fracture behaviour of Zr-based bulk metallic glass [J].Philosophical magazine letters,2005,85:513-521.
[249] DIVINSKI S V, RIBBE J, BAITHER D, SCHMITZ G, REGLITZ G, R SNER H,SATO K, ESTRIN Y,WILDE G. Nano-and micro-scale free volume in ultrafine grainedCu–1wt.%Pb alloy deformed by equal channel angular pressing [J]. Acta Materialia,2009,57:5706-5717.
[250] RIBBE J, BAITHER D, SCHMITZ G,DIVINSKI S V. Network of porosity formed inultrafine-grained copper produced by equal channel angular pressing [J]. Physical reviewletters,2009,102:165501.
[251] DIVINSKI S V, RIBBE J, REGLITZ G, ESTRIN Y,WILDE G. Percolating network ofultrafast transport channels in severely deformed nanocrystalline metals [J]. Journal ofApplied Physics,2009,106:063502.
[252] RIBBE J, BAITHER D, SCHMITZ G,DIVINSKI S V. Ultrafast diffusion and internalporosity in ultrafine-grained copper–lead alloy prepared by equal channel angular pressing[J]. Scripta Materialia,2009,61:129-132.
[253] EBRAHIMI F, LISCANO A, KONG D, ZHAI Q,LI H. Fracture of bulk face centeredcubic (FCC) metallic nanostructures [J]. Rev. Adv. Mater. Sci,2006,13:33-40.
[254] OVID'KO I A,SHEINERMAN A G. Nanocrack generation at dislocation-disclinationconfigurations in nanocrystalline metals and ceramics [J]. Physical Review B,2008,77:
[255] OVID'KO I A. Review on the fracture processes in nanocrystalline materials [J].Journal of Materials Science,2007,42:1694-1708.
[256] OVID'KO I A,SHEINERMAN A G. Suppression of nanocrack generation innanocrystalline materials under superplastic deformation [J]. Acta Materialia,2005,53:1347-1359.
[257] LU G,KAXIRAS E. Hydrogen embrittlement of aluminum: The crucial role ofvacancies [J]. Physical review letters,2005,94:155501.
[258] CHANDLER M Q, HORSTEMEYER M, BASKES M, WAGNER G, GULLETTP,JELINEK B. Hydrogen effects on nanovoid nucleation at nickel grain boundaries [J]. ActaMaterialia,2008,56:619-631.
[259] CHANDLER M Q, HORSTEMEYER M, BASKES M, GULLETT P, WAGNERG,JELINEK B. Hydrogen effects on nanovoid nucleation in face-centered cubicsingle-crystals [J]. Acta Materialia,2008,56:95-104.
[260] NEERAJ T, SRINIVASAN R,LI J. Hydrogen embrittlement of ferritic steels:Observations on deformation microstructure, nanoscale dimples and failure by nanovoiding[J]. Acta Materialia,2012,60:5160-5171.
[261] NAGUMO M. Hydrogen related failure of steels–a new aspect [J]. Materials Scienceand Technology,2004,20:940-950.
[262] WURSCHUM R, HERTH S,BROSSMANN U. Diffusion in nanocrystalline metalsand alloys-A status report [J]. Advanced Engineering Materials,2003,5:365-372.
[263] SHEN X, XU Z, LIAN J,JIANG Q. The deformation and fracture behavior of anelectrodeposited nanocrystalline Ni under compression [J]. Materials Science andEngineering a-Structural Materials Properties Microstructure and Processing,2011,528:7878-7886.
[264] REDDY K M, GUO J, SHINODA Y, FUJITA T, HIRATA A, SINGH J, MCCAULEYJ,CHEN M. Enhanced mechanical properties of nanocrystalline boron carbide bynanoporosity and interface phases [J]. Nature communications,2012,3:1052.
[265] LI H Q,EBRAHIMI F. Transition of deformation and fracture behaviors innanostructured face-centered-cubic metals [J]. Applied Physics Letters,2004,84:4307-4309.
[266] HANLON T, KWON Y N,SURESH S. Grain size effects on the fatigue response ofnanocrystalline metals [J]. Scripta Materialia,2003,49:675-680.
[267] YANG Y, IMASOGIE B, FAN G, LIAW P K,SOBOYEJO W. Fatigue and fracture of abulk nanocrystalline NiFe alloy [J]. Metallurgical and Materials Transactions A,2008,39:1145-1156.
[268] TABACHNIKOVA E, PODOLSKIY A, BENGUS V, SMIRNOV S, LI H, LIAW P,CHOO H, CSACH K,MISKUF J. Strain-Rate Sensitivity and Failure Peculiarities inCompression of the Nanocrystalline Ni-20Pct Fe Alloy at Low Temperatures [J].Metallurgical and Materials Transactions A,2010,41:848-853.
[269] SCHUH C A, NIEH T G,IWASAKI H. The effect of solid solution W additions on themechanical properties of nanocrystalline Ni [J]. Acta Materialia,2003,51:431-443.
[270] XIAO C H, MIRSHAMS R A, WHANG S H,YIN W M. Tensile behavior and fracturein nickel and carbon doped nanocrystalline nickel [J]. Materials Science and Engineeringa-Structural Materials Properties Microstructure and Processing,2001,301:35-43.
[271] ASARO R, KRYSL P,KAD B. Deformation mechanism transitions in nanoscale FCCmetals [J]. Philosophical Magazine Letters,2003,83:733-743.
[272] OVID'KO I A,SHEINERMAN A G. Grain size effect on crack blunting innanocrystalline materials [J]. Scripta Materialia,2009,60:627-630.
[273] OVID'KO I A,SHEINERMAN A G. Triple junction nanocracks in deformednanocrystalline materials [J]. Acta Materialia,2004,52:1201-1209.
[274] ZHANG X Y, WU X L, LIU Q, ZUO R L, ZHU A W, JIANG P,WEI Q M. Phasetransformation accommodated plasticity in nanocrystalline nickel [J]. Applied PhysicsLetters,2008,93:
[275] R SNER H, BOUCHARAT N, MARKMANN J, PADMANABHAN K,WILDE G. Insitu transmission electron microscopic observations of deformation and fracture processes innanocrystalline palladium and Pd90Au10[J]. Materials Science and Engineering: A,2009,525:102-106.
[276] ZHANG Z, ECKERT J,SCHULTZ L. Difference in compressive and tensile fracturemechanisms of Zr59Cu20Al10Ni8Ti3bulk metallic glass [J]. Acta Materialia,2003,51:1167-1179.
[277] WANG Y, LI J, HAMZA A V,BARBEE T W. Ductile crystalline–amorphousnanolaminates [J]. Proceedings of the National Academy of Sciences,2007,104:11155-11160.