热处理对Mg-4Y-3R_E合金微观组织和力学性能影响

Effect of Heat Treatment on Microstructure and Mechanical Properties of Mg-4Y-3R_E Alloy

采用熔铸法制备了Mg-4Y-3R_E-0.5Zr合金,利用固溶处理和时效处理;采用扫描电子显微镜(SEM)观察了合金的微观组织,利用能谱仪(EDS)对微区成分和析出相进行了分析,采用X射线衍射仪对合金的相组成进行分析。结果表明,Mg-4Y-3R_E-0.5Zr铸态合金由α-Mg和晶界处Mg-Y-Nd三元相组成,析出相为不规则的条状,固溶处理后晶界处三元相溶入基体,晶粒尺寸与铸态晶粒尺寸相差不明显。随着时效时间增加,晶粒尺寸无明显变化,时效2 h后,晶粒内部出现细针状和细小颗粒的析出相,且随时效时间延长析出相的数量明显增加。固溶+时效处理8 h后的合金比铸态合金的拉伸性能提高了30 MPa,而伸长率没有明显变化。

Mg-4Y-3RE-0.5Zr alloy was prepared by melting method with solid solution treatment and aging treatment.Microstructure was observed by scanning electron microscopy（SEM）, and phase composition were analyzed by X-ray diffraction. The results show that the grain size of Mg-4Y-3RE-0.5Zr alloy is in microns, and the alloy consists of α-Mg and Mg-Y-Nd phase in grain boundaries. After solution treatment, the Mg-Y-Nd phase in grain boundary dissolve into the matrix, and the grain size has not obvious different. With the aging time increasing, the grain size has no significant change, after the 2 hour aging, fine acicular and fine particles separates out in grains, and precipitates increases significantly with the aging time increasing. The tensile properties increase 30 MPa after solid solution and aging treatment 8 hours more than cast alloy while no significant changes in elongation.