Abstract:The effects of melt superheating and thermal-rate treatment on the mechanical properties, composition segregation, underside shrinkage and intergranular corrosion of ZA27 alloy were studied. The results showed that through proper treatment, the microstructure of the alloy was refined and well distributed, the tendencies of segregation, formation of underside shrinkage defects and intergranular corrosion were reduced, and the tensile strength and the hardness were improved obviously.According to the theory of multicrystal transformation, the mechanism of the property changes of ZA27 alloy was discussed.

Key words: ZA27 alloy; high-Al Zn-based alloy; thermal-rate treatment of melt