Effects of cooling rate and pressure on microstructure and mechanical properties of sub-rapidly solidified Mg–Zn–Sn–Al–Ca alloy
Effects of cooling rate and pressure on microstructure and mechanical properties of sub-rapidly solidified Mg–Zn–Sn–Al–Ca alloy
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DOI：
10.1016/j.matdes.2012.09.003
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发表时间：
2013-03
影响因子：
8.4
通讯作者：
Jihua Chen;Juying Wei;Hongge Yan;B. Su;X. Pan
中科院分区：
文献类型：
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作者：
Jihua Chen;Juying Wei;Hongge Yan;B. Su;X. Pan
通过金相显微镜、X射线衍射、扫描电镜和拉伸试验研究了冷却速率和压力对亚快速凝固Mg-6Zn-3Sn-2Al-0.2Ca合金显微组织和力学性能的影响。无压力钢型铸造制备的合金主要由α-Mg、Mg2Sn、MgZn和Mg32(Al,Zn)49 4个相组成，而水冷钢型加压铸造和水冷铜型加压铸造制备的合金主要由α-Mg、Mg2Sn、Mg51Zn20和Mg32(Al,Zn)49组成。较高的冷却速率促进晶界化合物的形成，而施加的压力对其有抑制作用。水冷铜型压力铸造合金具有所研究的5种合金中晶粒尺寸最细、枝晶臂间距最小、第二相更细、分布均匀的特点，表现出最佳的力学性能，极限抗拉强度、屈服强度和断裂伸长率分别为224MPa、157MPa和16.1%。与无压力钢型铸造制备的合金相比，水冷铜型铸造在压力下制备的合金以空洞聚结的韧性断裂特征为主。
Effects of cooling rate and pressure on microstructure and mechanical properties of sub-rapidly solidified Mg–6Zn–3Sn–2Al–0.2Ca alloy were investigated by OM, XRD, SEM and tensile testing. The alloy prepared by steel mould casting with no applied pressure is mainly composed of four phases i.e. α-Mg, Mg2Sn, MgZn and Mg32(Al,Zn)49, while those prepared by water-cooling steel mould casting under pressure and water-cooling copper mould casting under pressure consist of α-Mg, Mg2Sn, Mg51Zn20and Mg32(Al,Zn)49. The higher cooling rate promotes the formation of the grain boundary compounds, while the applied pressure has an inhibiting effect on it. The alloy prepared by water-cooling copper mould casting under pressure is characteristics of the finest grain size, the smallest dendrite arm spacing and the much finer, well-distributed second phases among the five as-studied alloys, exhibiting the optimal mechanical properties, with the ultimate tensile strength, the yield strength and elongation to rupture of 224MPa, 157MPa and 16.1% respectively. In comparison with the alloy prepared by steel mould casting with no applied pressure, the ductile fracture characteristics of void coalescence is dominant for the alloy prepared by water-cooling copper mould casting under pressure.