The influences of Al content on the microstructure and mechanical properties of as-cast Mg-6Zn magnesium alloys

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• 作者：Yu Zhang ; Xiaofeng Huang ; ^{huangxf_lut@163.com} ; Zhenduo Ma ; Ya Li ; Feng Guo ; Jianchang Yang ; Ying Ma ; Yuan Hao
• 关键词：Mg-6Zn magnesium alloy ; Al content ; Microstructure ; Mechanical property ; Fracture mode
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：16 February 2017
• 年：2017
• 卷：686
• 期：Complete
• 页码：93-101
• 全文大小：1904 K
• 卷排序：686

文摘

Mg-6Zn magnesium alloys microalloyed with varying Al content (0, 1, 3, 5 and 7 wt%) were prepared by permanent mould casting. The effects of Al on the microstructure and mechanical properties of as-cast Mg-6Zn alloy were characterized with an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS), an X-ray diffractometer (XRD) and mechanical tests at room temperature, respectively. The experimental results indicate that the grain sizes do not decline obviously while the amount of eutectic phase and the secondary dendrite arm spacing (SDAS) of the alloys gradually increase when the Al content exceeds 3%. The main phases α-Mg, MgZn2, Mg2Zn3, Mg7Zn3, MgZn, Mg32(Al, Zn)49 and Mg17Al12 are found in these alloys. A higher addition of Al (≥5 wt%) causes the formation of the Mg17Al12, meanwhile, the partial morphology of some eutectic phases is modified into lamellar formation, which has an adverse effect on mechanical properties of the Al-containing alloys. The mechanical testing reveals that, the tensile properties are gradually improved within the range of 0 ~ 3%Al, and the maximum values of ultimate tensile strength (UTS, 214 MPa) and elongation (EL, 8.7%) are simultaneously obtained from the alloy with 3% Al, which increases by 21 MPa and 16.0% compared with that of the ZA60 alloy, respectively. Fracture analysis demonstrates that quasi-cleavage fracture, inter-granular and trans-granular fracture are dominant modes in the alloy with additions of 0, 1, 3 wt% Al. In contrast, the rupture mechanisms of the other investigated alloys belong to cleavage and inter-granular fracture modes.