Influence of Heat Treatment on the Hardness of ZnAl22Cu3 Alloy

The effect of heat treatment on the structure and hardness of the ZnAl22Cu3 alloy is presented in the paper. ZnAl22 and ZnAl22Cu3 alloys were tested. The scope of the examination included dilatometry, structural and hardness tests. Very interesting is the effect of the transformation, occurring at lower temperatures on the structure and hardness of the alloy. There are found, that soaking at 185°C causes a decrease in the hardness of the ZnAl22Cu3 alloy. Observed ZnAl22Cu3 alloy hardness decrease is related to the disappearance of zinc-rich dendrites and the transition of zinc to a eutectoid mixture.