Effect of composition on the microstructure and mechanical properties of Mg–Zn–Al alloys
Effect of composition on the microstructure and mechanical properties of Mg–Zn–Al alloys
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DOI：
10.1016/j.msea.2006.11.089
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发表时间：
2007-05
期刊：
影响因子：
6.4
通讯作者：
Jing Zhang;Zhengxiao Guo;F. Pan;Zhongsheng Li;X. Luo
中科院分区：
文献类型：
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作者：
Jing Zhang;Zhengxiao Guo;F. Pan;Zhongsheng Li;X. Luo
镁在运输应用中受到极大关注，特别是其铸造合金。研究了金属型铸造Mg-Zn-Al合金的铸态组织和力学性能，该合金具有高锌铸造材料的典型成分。确定了三种类型的合金，并分别通过Mg32（Al，Zn）49（也称为τ相）、MgZn相（也称为α相）和三元二十面体准晶相（表示为Q相）表征。提出了一个示意性相图来显示显微组织成分随元素含量和Zn/Al比的变化。结果表明，合金的显微组织主要受Zn或Al含量和Zn/Al质量比的控制，Zn/Al比高、Al含量低的合金为α型，Zn/Al比中等、Al含量中等的合金为τ型，Zn/Al比低、Al含量高的合金为二十面体准晶相。在ZA系列合金中没有发现Mg_（17）Al_（12）（γ）相。讨论了凝固过程及其对相组成的影响。初步的力学性能测试表明，所有的实验合金具有相当的极限强度和屈服强度与AZ 91合金在室温下，但显示出更优越的上级抗蠕变性在高温下。此外，虽然室温性能仅取决于总元素含量，但τ型和Q型合金在改善高温性能方面显示出比τ型合金更大的潜力。
Magnesium is receiving great attention for transport applications, particularly its cast alloys. This investigation focuses on the as-cast microstructure and mechanical properties of permanent-mould cast Mg–Zn–Al alloys with typical compositions within the high zinc castable domain. Three types of alloys were identified and characterized by Mg32(Al, Zn)49, also known as the τ phase; MgZn phase, also known as the ɛ phase; and a ternary icosahedral quasi-crystalline phase, denoted as the Q phase, respectively. A schematic phase diagram is proposed to show the change of microstructral constituents with element content and the Zn/Al ratio. The diagram reveals that the microstructral constituent is dominated by both the content of Zn or Al and the Zn/Al mass ratio; alloys with a high Zn/Al ratio and a low Al content fall into the ɛ-type; alloys with an intermediate Zn/Al ratio and an intermediate Al content favour the τ-type; and those with a low Zn/Al ratio and a high Al are dominated by the icosahedral quasi-crystalline phase. No Mg17Al12(γ) phase was found in those ZA series alloys. The solidification process and its effects on the phase constituents were discussed. Preliminary mechanical property testing showed that all the experimental alloys possess comparable ultimate strength and yield strength with the AZ91 alloy at ambient temperature, but show far superior creep resistance at elevated temperatures. Moreover, while ambient-temperature properties solely depend on the total element contents, the τ- and the Q-type alloys show greater potential than the ɛ-type alloys on the improvement of elevated temperature properties.