根据合金成分设计, 在Mg-5Sn铸造合金中逐步添加2%Al及4%Zn(质量分数), 实验结果表明,单独添加Al后, 一次枝晶尺寸减小, 且二次臂变的更加细密, 合金的延伸率从6.6%提高到22.4%; Al和Zn复合添加后, 长程枝晶转变为较为圆整的蔷薇状, 在合金中生成了Mg₃₂(Al, Zn)₄₉相,合金的屈服强度和抗拉强度分别达到96和232 MPa, 但延伸率则下降到14.8%. 通过固溶时效处理,Mg-5Sn-4Zn-2Al合金在175 ℃时效24 h后达到硬度峰值83.5 HV, 其晶内析出相由沿[0001]晶向分布的MgZn₂和块状的Mg₂Sn相组成, 对应的室温屈服和抗拉强度分别提升到144和264 MPa; 在150 ℃下其屈服强度仍可达到138 MPa, 这表明合金的晶内析出的MgZn₂和Mg₂Sn相在高温下仍具有良好的强化作用.

A cast Mg-5Sn-4Zn-2Al alloy was developed by adding 2%Al and 4%Zn (mass fraction) into a Mg-5Sn base alloy. The results showed that the combined addition of Al and Zn had more obvious effect on dendrite refinement than the single Al addition. The single Al addition remarkably increased the elongation from 6.6% to 22.4%. With further addition of Zn, Mg₃₂(Al, Zn)₄₉ phase was introduced into the solidified microstructure, and the yield strength and ultimate tensile strength were increased to 96 and 232 MPa while elongation was decreased to 14.8%. After aging treatment at 175 ℃ for 24 h, there appeared peak hardness of 83.5 HV by forming the rod-shaped MgZn₂ along c-axis and cubic Mg₂Sn precipitates into α-Mg matrix for Mg-5Sn-4Zn-2Al alloy. With the aging strengthening, the yield strength and ultimate tensile strength were further increased to 144 and 264 MPa, respectively. When the testing temperature was elevated to 150 ℃, the yield strength of peak-aged Mg-5Sn-4Zn-2Al alloy still attained to 138 MPa, which indicated that both the MgZn₂ and Mg₂Sn precipitates possess good thermal stability for elevated temperature property.