Effect of rate dependence of crack propagation processes on amorphization in Al

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• 作者：Peng-tao Li ; Yan-qing Yang ; ^{yangyanqing05@163.com} ; Xian Luo ; Na Jin ; Gang Liu ; Chong-de Kou ; Zong-qiang Feng
• 关键词：Crack tip ; Plastic deformation ; Twinning ; Amorphization ; MD simulation
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：27 January 2017
• 年：2017
• 卷：684
• 期：Complete
• 页码：71-77
• 全文大小：2524 K
• 卷排序：684

文摘

Uniaxial tension of pure Al is studied at different loading rates by molecular dynamics simulation to understand the initial nucleation processes for amorphous structures and twinning, especially, the competition between twinning partial dislocation and Lomer one. There exists a transition point KI=0.205 eV Å−2.5 between twinning partial dislocation and Lomer one, with Lomer dislocation preferable at high loads. A modified Peierls analytic model is established to describe the transition process. The analytic model reflects that a transition from twinning partial dislocation to Lomer one will occur when stress intensity factor KI reaches 0.205 eV Å−2.5, which is similar to the simulation trends. In addition, amorphization behaviours are observed at crack tip in pure Al by in-situ straining transmission electron microscopy. Both the experiment and simulation results are demonstrated that amorphization behaviours occur at crack tip in FCC Al.