Effect of Al Content and Heat Treatment on Microstructure of ZnAlCu Alloys

The work analyses microstructures of ZnAl4Cu1, ZnAl27Cu2 and ZnAl40Cu2Si2 alloys in cast condition and after heat treatment in relation to microhardness HV0.2 and purity of the alloys. As shown the microstructure of ZnAl4Cu1 alloy contained η phase and eutectoid, which consisted phases α + η. ZnAl27Cu2 alloy contained α phase, eutectoid and ε phase, and ZnAl40Cu2Si2 alloy had a similar composition, but moreover contained Si particles. Microhardness in the molten state in ZnAl4Cu1 alloy was HV0.2 = 94, in ZnAl27Cu2 alloy it was HV0.2 = 117, and in ZnAl40Cu2Si2 alloy it was HV0.2 = 142.