Investigation of microstructure, mechanical and tribological properti̇es of zn-40Al based alloys

In this study, Zn-40Al-2Cu-(0-2.5)Ni alloys and Zn-40Al-2Cu-2Si alloy were produced by permanent mould casting. The Zn-40Al-2Cu-2Si alloy was tested in both as-cast and heat treated conditions, but the Zn-40Al-2Cu-(0-2,5)Ni alloys were tested only in the as-cast condition. After examining the structural and mechanical properties of the alloys, their tribological properties were investigated using a block-on-cylinder type test machine. It was observed that the hardness, friction coefficient and working temperature of Zn-40Al-2Cu-(0,5-2,5)Ni alloys increase, their strength and ductility decrease, but their average surface roughness and volume loss show different changes with increasing nickel content. T5, T6 and air cooling heat treatments reduced the friction coefficient, working temperature and volume loss of Zn-40Al-2Cu-2Si alloy, but furnace cooling and T7 heat treatment increased the values of these parameters. These parameters showed opposite changes with the average surface roughness of the wear samples. As the isothermal transformation temperature increased the friction coefficient, working temperature and volume loss of Zn-40Al-2Cu-2Si alloy increased, but its average surface roughness decreased. As a result this work it was concluded that the solutionizing followed by air cooling, T6 heat treatment and isothermal transformation at 100 °C increase hardness, tensile strength and wear resistance of Zn-40Al-2Cu-2Si alloy.