流变压铸AM60镁合金在固溶处理过程中的组织演变

Microstructure evolution of rheo-diecast AM60 magnesium alloy during solution treatment

采用光学显微镜(OM)、扫描电镜(SEM),研究了固溶处理对流变压铸AM60镁合金组织及硬度的影响。结果表明,流变压铸成形的AM60镁合金在430℃固溶处理24 h后,AM60镁合金晶界及枝晶间的粗大网状β-Mg17Al12相几乎全部消除,只剩少量、不连续状的β-Mg17Al12相残留在晶界,α-Mg基体中出现少量细小颗粒状β-Mg17Al12相,α-Mg基体中的Al含量显著增加。而且,随着固溶时间的延长,流变压铸成形AM60镁合金组织中的初生颗粒与二次凝固区颗粒出现合并长大现象,它们的长大速率都随固溶时间的延长而降低,随固溶温度的升高而增大。

Effect of solution treatment on microstructure and hardness of AM60 magnesium alloy rheo-diecast was investigated by using optical microscope（OM） and scanning electron microscope（SEM）. The results show that when the rheo-diecast AM60 magnesium alloy was solutionized at 430 ℃ for 24 h, the coarse and net β-Mg17Al12 phase distributed along the grain boundaries and dendrite is almost dissolved after solution treatment, only a little β-Mg17 Al12 phase discontinuously distributes along the grain boundary, a little fine grain β-Mg17 A1,2 phase appears in the a-Mg matrix and the content of A1 in the oL-Mg matrix increases remarkably. With the increase of solution treatment time, the coalescent growth oecurres for both the primary particles and the secondary solidification particles in the rheo-dieeast AM60 alloy, and the growth rate decreases with the increase of solution time and increases with the increase of solution temperature.