等温热处理对ZA63镁合金半固态组织演变的影响

Effects of Isothermal Heat Treatment on Microstructural Evolution of ZA63 Magnesium Alloy

采用等温热处理法对ZA63合金在不同的保温温度及保温时间下的半固态组织的演变过程和机理进行了研究。结果表明,通过半固态等温热处理能够制备ZA63非枝晶组织,并获得细小、分布均匀的球状颗粒。非枝晶组织演变经历了粗化、枝晶分离、球化以及晶粒的合并和长大4个过程。ZA63合金半固态触变成形最适合的等温热处理工艺是590℃×20min,平均晶粒尺寸、圆整度和固相率分别为59.16μm、1.5和43%。

The semi-solid non-dendritic microstructure evolution and mechanism of ZA63 magnesium alloy at varied holding temperature and time were investigated by isothermal heat-treatment.The results show that ZA63 alloy with the non-dendritic microstructure can be prepared by semi-solid isothermal heat-treatment,and fine spherical particles with uniform distribution can be obtained.The evolution of non-dendritic microstructure has undergone coarsening,dendrite separation,spheroidization and mergence growth.The optimal heat treatment parameters are reheating at 590 ℃for 20 min for semi-solid thixoforming of the alloy,where the grain size,roundness and solid fraction reach 59.16μm,1.5and43%,respectively.