采用光学显微镜 、X射线衍射仪、扫描电镜和拉伸试验机等研究了固溶处理工艺对挤压铸造态AZ81E镁合金显微组织与性能的影响。结果表明: 该镁合金在350~420 ℃固溶处理后, 随着固溶温度的升高和保温时间的延长, 粗大网状β-Mg17Al12相逐渐溶解; 经400 ℃固溶处理8 h后, 枝晶偏析得到有效消除, 稀土相得到细化并部分固溶到基体内; 随着固溶处理保温时间的延长, 合金硬度先下降后升高, 保温8 h硬度达到最低, 为59 HRE, 力学性能较铸态合金的有较大提升, 其中400 ℃固溶8 h的综合性能最好; 固溶处理前合金的室温拉伸断口为准解理断裂和韧性断裂的混合断口, 经固溶处理后变为韧性穿晶断裂。

The effect of solution treatment on microstructure and properties of the squeeze casting AZ81E magnesium alloy was researched by optical microscope, X-ray diffraction, SEM and tensile tester. The results show that after solution treatment at 350-420 ℃, coarse and netlike β-Mg17Al12 phase dissolved gradually with the rise of solution temperature and extension of holding time. After solution at 400 ℃ for 8 h, the dendrite segregation had been effectively eliminated, RE phase became finner and was partly soluted to the base body. With the extension of holding time, hardness of the alloy decreased first and then rised. The minimum hardness of 59 HRE could be obtained when the holding time was 8 h. And the mechanical properties were improved significantly and at 400 ℃ the over-all properties were the best. After solution treatment, the tensile fracture mode at room temperature transformed from the mixture of quasi-cleavage fracture and ductile fracture to ductility transgranular fracture.