The Zn22wt%Al alloy has a complex microstructure due to eutectoid transformation (β → α + η) in cases of as-casting and after quench-aging conditions. The objective of this work was to investigate the relationship between the solidification rate and the morphology of α and η phases, before and after quench-aging. The samples of the Zn-22wt%Al alloy were analyzed by scanning electron microscopy (SEM) and by EDS (Energy Dispersive Spectroscopy). The as-casting samples presented a lamellar structure while the as-aged ones exhibited a quasi-globular morphology. The results showed that the hardness of the samples strongly depends on the α + η phase morphology. On the other side, the chemical composition and morphology of the phases depends on the solidification and cooling rates.
Zinc-aluminum alloys; solidification; phase transformation
