通过光学显微镜、扫描电镜观察和拉伸、压缩试验研究了在不同温度下Mg-11Y-5Gd-2Zn-0.5Zr(WGZ115)镁合金的拉压不对称性及其原因.结果表明:该合金在低于200℃拉伸时发生脆断,在200~300℃内拉伸屈服强度大于压缩屈服强度,在300℃时拉伸屈服强度与压缩屈服强度相等,在高于300℃后拉伸屈服强度小于压缩屈服强度;相同温度下该合金抗压强度大于抗拉强度,压缩的最大应变量大于拉伸的最大应变量;在拉伸时,合金裂纹多为穿晶扩展,二次裂纹导致合金在25~200℃迅速脆断;在压缩时,合金内部出现孪晶带,使其压缩变形能力增强.

The asymmetry of tension and compression of Mg-11Y-5Gd-2Zn-0.5Zr (WGZ115) magnesium alloy and its reason were studied through optical microscopy and scanning electron microscopy observation as well as tension and compression test at different temperatures.The results show that brittle rupture of the alloy occured during tensile test under 200℃.The tensile yield strength was higher than the compressive yield strength as the temperature was between 200℃ and 300℃,and the former was equal to the latter as the temperature was 300℃.While the former was lower than the latter as the temperature was higher than 300℃.Under the same temperature the compressive yield strength was higher than the tensile yield strength,and the maximum compressive strain was larger than the maximum tensile strain.The cracks were main transgranular extension during tension,and the secondary cracks led to brittle fracture rapidly at 25℃ to 200℃.Twin bands formed in the alloy during compression,and the alloy had good compression workability.