双级时效热处理ZM5合金的显微组织和力学性能

以ZM5合金为研究对象,通过显微组织分析和力学性能测试等手段,研究了其不同状态的显微组织和力学性能。结果表明,铸态ZM5合金中存在呈网状分布的粗大不规则块状β-Mg₁₇Al₁₂相;固溶处理后,β-Mg₁₇Al₁₂相溶入α-Mg基体中,仅有少量残余的AlMn相;经T6处理后,沿晶界析出片层状β-Mg₁₇Al₁₂相;经双级时效处理后,沿晶界析出片层状β-Mg₁₇Al₁₂相及在晶内析出细小的针片状β-Mg₁₇Al₁₂相。与铸态相比,热处理后ZM5合金的抗拉强度大幅提升;经双级时效处理后,其抗拉强度可达285MPa,比T6处理后的抗拉强度高20MPa。

Microstructure and Mechanical Properties of ZM5 Alloy Treated by Two Stage Aging

The microstructure and mechanical behavior of ZM5 alloy with different conditions were carried out by microstructural analysis and tensile testing.The results reveal that there exist many coarse blockyβ-Mg₁₇Al₁₂ phase in as-cast ZM5 alloy,which is distributed in form of netlike on the grain boundary.After solution treatment,theβ-Mg₁₇Al₁₂ phase is dissolved intoα-Mg matrix,and a few Al-Mn phase remains.The lamellarβ-Mg₁₇Al₁₂ phase is precipitated along the grain boundary in ZM5 alloy after T6 treatment.After two stage aging treatment,the lamellarβ-Mg₁₇Al₁₂ phase is precipitated along the grain boundary and fine acicularβ-Mg₁₇Al₁₂ phase is precipitated inside grain.Compared to that of as-cast ZM5 alloy,the ultimate tensile strength of heat treated ZM5 alloy is enhanced greatly.The ultimate tensile strength of ZM5 alloy treated by two stage aging can reach 285 MPa,which is 20 MPa higher than that of ZM5 alloy treated by T6.