Microstructure and creep properties of Mg-4Al-2Sn-1(Ca,Sr) alloys

The effects of Ca and Sr addition on the microstructure and creep properties of Mg-4Al-2Sn alloys were examined. Tensile tests at 25 °C and 200 °C and creep tests at 150 °C and 200 °C were carried out to estimate the room temperature and high temperature mechanical properties of these alloys. The microstructure of the Mg-4Al-2Sn alloy showed dendritic α-Mg, Mg17Al12 and Mg2Sn phases. The latter two phases precipitated along the grain boundaries. The addition of Ca and Sr resulted in the formation of ternary CaMgSn and SrMgSn phases within the grain. The grain size was reduced slightly with the addition of Sr and Ca. The tensile strength was decreased by the addition of Ca and Sr at room temperature. However, the high temperature tensile strength was increased. The creep strength was improved by the addition of Ca and Sr.