Effect of heat treatment on the mechanical properties of Al-Zn & Al-Zn-Cu alloys

In this research work, binary Al-25Zn and ternary Al-25Zn-3Cu alloys were fabricated using stir casting process. Microstructure and mechanical properties of as-cast alloys were foundout and the composition of the alloys was validated using energy dispersive X-ray analysis (EDX). The fabricated alloys were solution treated at 450 °C for 10 hours and then artificially aged at different temperatures (100 °C, 150 °C and 200 °C), each at 1 hour, 2 hours, 3 hours and4 hours. The microstructure after heat treatment was compared with the as-cast microstructure. Hardness and tensile properties were investigated for both as-cast and heat-treated alloys. Al-25Zn-3Cu alloy exhibits superior strength (hardness and tensile) when compared to Al-25Zn alloy in both as-cast and heat-treated conditions. Higher hardness and tensile strength were obtained at the aging temperature of 100 °C for 1 hour, for both alloys. The results were validatedusing scanning electron microscope (SEM) microstructures and X-ray diffraction (XRD).