Effect of phase transformations on hardness in Zn-Al-Cu alloys

Abstract

Zn-Al-Cu alloys were prepared by melting of pure elements. The as-cast alloys were homogenized at 350 °C for 180 h. Both the as-cast and homogenized alloys were analyzed with X-ray diffraction and scanning electron microscope with Energy Dispersive X-Ray analysis. The hardness of alloys was determined using Rockwell “B” hardness. The X-ray diffractograms and scanning electron micrographs indicated the presence of several phases in the as-cast alloys. Some of them do not correspond to those shown in the equilibrium Zn-Al-Cu phase diagram. On the other hand, the homogenized alloys showed most of the phases present in the equilibrium diagram. The hardness of alloys increases with the increase in Cu content because of the presence of Cu-containing phases such as, the θ and τ phases.