Effect of Zn addition on the microstructure and mechanical properties of the as-cast and ECAPed Mg15Al alloy
Effect of Zn addition on the microstructure and mechanical properties of the as-cast and ECAPed Mg15Al alloy
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发表时间：
2013
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通讯作者：
Cao Xiao-qing
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作者：
Cao Xiao-qing
采用OM、XRD、SEM等分析手段研究了铸态和等通道转角挤压（ECAP）后Mg 15 Al合金和Mg 15 Al-1 Zn合金的显微组织和力学性能，结果表明，Zn元素主要固溶在β-Mg 17 Al 12相中，没有新相出现，当Zn元素含量为1wt%时，铸态Mg 15 Al合金的晶粒尺寸减小随着β-Mg_（17）Al_（12）含量的增加，α-Mg基体中有网状β-Mg_（17）Al_（12）相生成。经ECAP变形后，α-Mg基体的晶粒尺寸由11.3μm急剧减小（在Mg 15 Al中）至8.73μm（Mg 15 Al-1 Zn中），β-Mg 17 Al 12相的网状结构消失，形貌发生改变，ECAP改善了Mg 15 Al-1 Zn和Mg 15 Al合金的力学性能，其抗拉强度分别比铸态提高了86%和60%，且Mg 15 Al-1%Zn合金的提高量大于Mg 15 Al合金，在屈服强度和延伸率变化不大的情况下，室温抗拉强度可达61.8MPa左右，Zn的加入强烈促进了ECAP过程中晶粒的细化和β相的破碎，进一步提高了合金的力学性能。
Microstructures and mechanical properties of the as-cast and equal channel angular pressed(ECAPed) Mg15Al alloy and Mg15Al-1Zn alloy were investigated by OM,XRD,SEM,EDS and the tensile tests in this paper.The results show that Zn element added to Mg15Al alloy mainly dissolved into the β-Mg17Al12 phase and no new phase presented.The grain size of the as-cast Mg15Al alloy was decreased with addition of 1wt% Zn element,meanwhile,net-work β-Mg17Al12 phases tend to form with the increasing amount of β-Mg17Al12.After processing by ECAP,the grain size of α-Mg matrix was decreased sharply,from 11.3μm(in Mg15Al) to 8.73μm(in Mg15Al-1Zn) and the net structure of β-Mg17Al12 phase was disappeared and the morphology was modified.As a result,the mechanical properties of Mg15Al-1Zn and Mg15Al alloy were improved by ECAP,and the tensile strength of Mg15Al-1Zn alloy and Mg15Al alloy was increased by 86% and 60% respectively compared with its as-cast state.Moreover,the increased amount of ECAPed Mg15Al-1%Zn alloy was greater than that of ECAPed Mg15Al,about 61.8MPa in room temperature tensile strength under the condition of the yield strength and elongation changing little.It's significant to notice that the grain refinement and β phase fragmentation during ECAP processing was strongly promoted and the mechanical properties of the alloy was further improved by the action of Zn addition.