Effect of Al content on the microstructures and mechanical properties of Mg–Al alloys

A preliminary investigation has been carried to evaluate the influence of Al content on the microstructures and mechanical properties of Mg–Al alloys in as-cast condition. Three types of Mg–Al alloys were studied and characterized by Mg–10Al–Zn, Mg–20Al–Zn and Mg–44Al, respectively. The results indicate that the microstructures of all three alloys mainly consist of α-Mg solid solution, β-Mg17Al12 and the eutectic mixture (α-Mg + β-Mg17Al12). Increasing the Al content leads to the microstructures changes and increase the micro-hardness of the Mg–Al alloys. When the Al content increases to 44 wt%, the main phase of the alloy is β-Mg17Al12 and the micro-hardness reaches to about 280 (HV). The reasons for these changes were also discussed in this paper.