稀土元素Gd对Mg-Zn-Zr镁合金组织和性能的影响  

Effect of Gadolinium on Microstructure and the Mechanical Properties of Mg-Zn-Zr Cast Magnesium Alloys

作　　者：李杰华[1] 介万奇[1] 杨光昱[1] 

机构地区：[1]西北工业大学,陕西西安710072

出　　处：《稀有金属材料与工程》2008年第9期1587-1591,共5页Rare Metal Materials and Engineering

基　　金：国家基础研究发展规划资助项目(G2000067202);西北工业大学博士论文创新基金资助(CX200705)

摘　　要：通过砂型铸造制备Mg-5Zn-0.6Zr和Mg-5Zn-3Gd-0.6Zr合金,并通过XRD、OM、SEM和EDS以及拉伸试验研究合金化稀土元素Gd对Mg-5Zn-0.6Zr合金铸造组织和力学性能的影响。结果表明:合金Mg-5Zn-0.6Zr铸态组织由α-Mg和MgZn2等合金相组成。经固溶处理后,共晶组织全部溶入基体,晶界消失;添加合金化元素Gd后,试验合金Mg-5Zn-3Gd-0.6Zr的晶粒显著细化,晶界处析出Mg-Zn-Gd三元相,在晶界析出相的周围均有大量弥散的颗粒状析出物,经固溶处理后,晶界处仍有未溶的化合物存在,但连续网状的Mg-Zn-Gd三元相分解为孤立的颗粒状或者长条状;在铸态下,合金Mg-5Zn-0.6Zr的力学性能优于Mg-5Zn-3Gd-0.6Zr。但经T4和T6态热处理后,合金Mg-5Zn-3Gd-0.6Zr的屈服强度和延伸率优于Mg-5Zn-0.6Zr。随着温度的升高,合金Mg-5Zn-0.6Zr的抗拉伸强度显著下降,而Mg-5Zn-3Gd-0.6Zr的力学性能在高温区均优于Mg-5Zn-0.6Zr。Mg-5Zn-0.6Zr and Mg-5Zn-3Gd-0.6Zr were prepared by sand casting. The effects of Gd addition on the microstructure and properties of Mg-5Zn-0.6Zr magnesium alloy were studied by XRD, OM, SEM, EDS and mechanical property tests. The results show that： as-cast microstructure in Mg-5Zn-0.6Zr alloy consists of a-Mg grains with MgZn2 phase on the grain boundary, while microstructure in Mg-5Zn-3Gd-0.6Zr alloy also is a ternary Mg-Zn-Gd phase on the α-Mg grain boundary with finer structure. A large amount of dispersive particles of Mg-Zn-Gd phase are formed nearby the grain boundary. After solution heat-treatment, eutectic in Mg-5Zn-0.6Zr alloy is fully dissolved into the matrix, in which the microstructure in Mg-5Zn-3Gd-0.6Zr is fined obviously. However, there is still Mg-Zn-Gd phase on the grain boundary of Mg-5Zn-3Gd-0.6Zr alloy. Moreover, the morphology of Mg-Zn-Gd phase was changed from net into insular. The as-cast mechanical property of Mg-5Zn-0.6Zr alloy is higher than that of Mg-5Zn-3Gd-0.6Zr alloy. After T4 and T6 heat-treatment, the yield strength and the elongation of Mg-5Zn-3Gd-0.6Zr alloy becomes higher than that of Mg-5Zn-0.6Zr alloy. With the increase of temperature, the ultimate strength and yield strength of Mg-5Zn-0.6Zr alloy at elevated temperature decrease sharply. At elevated temperature the mechanical property of Mg-5Zn-3Gd-0.6Zr alloy is better than that of Mg-5Zn-0.6Zr alloy.

关 键 词：力学性能 Mg—Zn-Zr合金 固溶处理 稀土Gd 

分 类 号：TG113[金属学及工艺—物理冶金]