Structure and mechanical properties of Zn-(5–25) Al alloys

Abstract

Abstract In order to determine the most suitable chemical composition for the basis of zinc-based ternary and quaternary alloys, five binary Zn-(5–25) Al alloys were prepared by permanent mould casting. Their microstructures and mechanical properties were investigated using metallography and hardness, tensile and compression tests. The microstructure of Zn-5Al alloy consisted of eutectoid α + η and eutectic η phases. However, the microstructures of relatively high aluminium-containing alloys (Zn-10Al and Zn-15Al) consisted of proeutectic β dendrites surrounded by η phase and small rounded α particles. The near eutectoid alloys (Zn-20Al and Zn-25Al) exhibited similar microstructures to those of Zn-10Al and Zn-15Al alloys, but with α-cored β dendrites surrounded by α + η particles. As the aluminium content increased the hardness and strength of the alloys increased, but their impact energy and density decreased. The total percentage elongation of the alloys also decreased with aluminium content, but after showing an initial increase. These observations are discussed in terms of the microstructural features of the alloys.