Effect of melt overheating treatment on the microstructure and mechanical properties of Zn-Al alloy

This study focused on the effect of overheating treatment on the microstructure and tensile mechanical property of zinc-aluminum alloy. Ingots with designed composition were manufactured by melting pure metals and cast at different temperatures from 500 degrees C to 650 degrees C. Microstructure, strength and fracture mechanism were studied and their relationships with overheating temperature were analyzed. Dendrite size decreased with increasing overheating temperature and turned to equiaxed crystal at 650 degrees C. The yield stress, ultimate tensile stress and elongation increased by 16%, 31% and 163%, respectively after overheating treatment. It was also found that with the increase of overheating temperature, the brittle fracture mechanism gradually turns to a mixed fracture mechanism.