Gd和Y偏析对Mg-9Gd-4Y-0.6Zr和Mg-7Gd-4Y-0.6Zr合金组织性能的影响

来源期刊：中南大学学报(自然科学版)2007年第1期

论文作者：肖　阳 张新明 蒋浩 陈部湘

文章页码：24 - 29

关键词：Mg-Gd-Y-Zr合金；耐热镁稀土合金；偏析

Key words：Mg-Gd-Y-Zr alloy; heat resistant magnesium-rare earth alloy; segregation

摘    要：利用光学显微镜、扫描电镜、透射电镜及能谱分析对Mg-9Gd-4Y-0.6Zr合金和Mg-7Gd-4Y-0.6Zr进行组织观察。结果表明：Gd和Y元素容易产生如枝晶偏析、晶界偏析和重力偏析等严重的局部组织缺陷；Gd元素偏析程度比Y的大，降低Gd的含量能减少合金的偏析；Mg-7Gd-4Y-0.6Zr的偏析程度比Mg-9Gd-4Y-0.6Zr的低；Mg-7Gd-4Y-0.6Zr合金经固溶处理后基本上消除偏析，并且该合金的强度损失较少，延伸率大幅度提高，这有利于提高合金的综合力学性能；Mg-9Gd-4Y-0.6Zr合金中稀土元素偏析形成的稀土粒子能塞积位错和阻碍晶界运动，是合金变形过程中形成裂纹的源头，能降低合金的塑性，并对合金的断裂产生较大影响。

Abstract: The microstructures of Mg-9Gd-4Y-0.6Zr and Mg-7Gd-4Y-0.6Zr alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersion X-ray analysis. The results show that the segregation of Gd and Y elements leads to many local defects such as dendritic segregation, grain-boundary segregation and gravity segregation. The degree of Gd segregation is larger than that of Y, and it can be reduced by decreasing Gd concentration. The segregation degree of Mg-7Gd-4Y-0.6Zr is smaller than that of Mg-9Gd-4Y-0.6Zr, and it can be eliminated almost completely by solution heat treatment. The strength of Mg-7Gd-4Y-0.6Zr reduces less and the elongation of this alloy rises more, which is useful to improve the combiation mechanical properties. The particles formed by the rare earth segregation can pile-up dislocations and inhibit grain boundary motion, but these particles are sites of crack initiation, resulting in lower plasticity and exerting influence on fracture mode of the alloy.

基金信息：国家基础研究项目
国家“863”计划项目
国家“863”计划项目