熔炼制备了不同锶含量的Mg-8%Li-3%Zn(质量分数)合金, 通过光学显微镜和拉伸试验机研究了元素锶对不同状态合金显微组织和力学性能的影响。结果表明: 随着锶的加入, 铸态合金中出现沿晶界网状分布的含锶化合物, 使铸态合金呈脆性断裂; 随着锶含量的增加, 铸态合金的强度和伸长率均下降; 合金经挤压后, 网状分布的锶化合物变为细小的块状, 弥散分布在合金组织中, 强度和塑性都得到了很大的提高; 随着锶含量的增加, 挤压态合金强度先增大后下降, 塑性则呈下降趋势; 挤压态合金经重熔再挤压后, 其抗拉强度与屈服强度比挤压态合金的分别提高了15%与30%, 而塑性微降。

Mg-8Li-3Zn-xSr alloys with different Sr mass fractions were prepared by smelting. The effects of Sr on the microstructure and mechanical properties of the alloys in different states were investigated by optical microscopy and tensile testing. The results show that network structure compounds of Sr in the grain boundaries could be found in the cast alloy with addition of Sr, which led to brittle fracture. With the increase of Sr content, both the strength and the elongation of the cast alloys decreased. The network structure compounds of Sr were broken to tiny masses distributing dispersively in the microstructure after extrusion, which could improve the strength and ductility of the alloy. With the increase of Sr content, the strength of the extruded alloys firstly increased and then decreased, and the ductility showed a downward trend after extrusion. The tensile strength and yield strength of the extruded alloy after remelting enhanced by 15% and 30%, respectively, and the ductility decreased a little, compared with the extruded alloy.