Abstract: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.

Key words: Mg−Zn−Al system; isothermal section; solubility; intermetallic compound