Isothermal section of the Mg-Al-Mn ternary system at 400 °C

In this work, the equilibrium phase constituents and compositions in the Mg-Al-Mn ternary system at 400 °C were determined through equilibrated alloy method and diffusion couple technique by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe micro-analyzer (EPMA). The isothermal section in the Mg-rich corner at 400 °C was thus constructed. No ternary compounds were detected in the Mg-rich corner. Therefore, there exist the equilibrium relationships between the α-Mg solid solution and Mg17Al12 compound or the other Al-Mn compound phases. The solubility of Mn in the phases α-Mg and Mg17Al12 is almost negligible, while the element Mg can slightly dissolve in the compound Al11Mn4. The lattice parameter dependence of α-Mg solid solution on Al content in Mg-Al-Mn system was finally determined by the XRD results.