Phase equilibria of Mg-rich corner in Mg-Zn-Al ternary system at 300 °C

The phase equilibria and compositions in Mg-rich corner at 300 °C were determined in the Mg-Zn-Al ternary system through the equilibrated alloy method by using X-ray diffraction (XRD) and scanning electron microscopy (SEM) assisted with energy dispersive spectroscopy of X-ray (EDS). The results show that there exist three three-phase regions consisted of α-Mg+Mg17Al12(γ)+Al5Mg11Zn4(ϕ), α-Mg+Mg32(Al, Zn)49(τ)+Al5Mg11Zn4(ϕ) and α-Mg+MgZn+Mg32(Al, Zn)49(τ), respectively. The intermetallic compounds in equilibrium with α-Mg phase all have large composition ranges, not appear to be linear. At the same time, both zinc and aluminum are soluble in the α-Mg solid solution, with which the compounds are in equilibrium.