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。
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.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2007年第1期24-29,共6页
Journal of Central South University:Science and Technology
基金
国家基础研究项目(5133001E)
国家"863"计划项目(2004AA741062
2003AA741043)
