均匀化处理对Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y合金组织和硬度的影响（英文）

Effect of Homogenization on Microstructure and Mechanical Property of Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y Alloy

采用差热分析(DSC),金相显微镜(OM),扫描电镜(SEM),能谱分析(EDS)和X射线衍射研究了Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y合金均匀化过程中微观组织演化;另外,测试了维氏硬度。研究发现,铸态Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y合金包含:和相。铸态试样的吸热峰在510℃,合金经500℃,16h均匀化处理后吸热峰消失。经470和490℃均匀化处理后,少量的W相溶解;而经过500℃,16h均匀化处理后,仅有少量W,I和X相存在,枝晶偏析基本消除,最佳均匀处理工艺为500℃,16h。均匀化处理可以将Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y合金的硬度从1852降到1442MPa,这样有利于后续塑性变形。

The microstructure evolution of Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y alloy during homogenization was investigated by differential thermal analysis（DSC）,optical microscopy（OM）,scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）and X-ray diffraction.Meanwhile,the Viker’s hardness（HV）was tested.Results show that the microstructure of as-cast Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y alloy consists ofα-Mg,（W）,Zn-Zr,（X）and Mg3（Y,Nd）Zn-6（I） phases.The as-cast sample has an endothermic peak at 510℃,which disappears in the alloy homogenized at 500℃ for 16h.A small quantity of W phases dissolve at 470 and 490℃.However,after homogenization at 500℃ for 16h,there is only a small number of W,I and X phases,and dendritic segregation is almost eliminated.Therefore,the optimum homogenization parameter is 500℃ for 16h.Homogenization can effectively decrease the hardness of the as-cast Mg-5.9Zn-1.6Zr-1.6Nd-0.9Y alloy from 1852MPa to 1442MPa,so it is beneficial to further deformation of the alloy.