Investigation of properties and microstructures of Mg-Al-Cu sand-cast magnesium alloys

The microstructures and mechanical properties of AC33, AC53 and AC63 alloys were investigated. It is found that the phase constitutions of all three experimental alloys are the same, i.e. δ-Mg, Mg₁₇Al₁₂ and Mg₂Al₂Cu₃.The ambient temperature mechanical properties of sand-cast experimental alloys are suitable for the demands of the general structural parts. The creep resistances of the experimental alloys are apparently better than that of AZ91C. The elevated temperature creep rate of AC53 alloy is the lowest among them. The effects of Cu addition on the elevated temperature creep behaviors could be explained as follows: Addition of 3%Cu in Mg-(3-6)%A1 alloys suppresses forming of Mg₁₇Al₁₂ phase, which might play an important role on the creep behavior.