Effects of minor Sr addition on as-cast microstructure and mechanical properties of a Mg-3Sn-2Ca (wt.%) magnesium alloy

Minor Sr was introduced to the Mg-3Sn-2Ca (wt.%) alloy in this paper, and the effects of minor Sr addition on the as-cast microstructure and mechanical properties of the Mg-3Sn-2Ca (wt.%) alloy were investigated by using of optical and electron microscopies, differential scanning calorimetry (DSC) analysis, and tensile and creep tests. The results indicate that, after adding 0.034wt.%, 0.065wt.% or 0.10wt.% Sr to the Mg-3Sn-2Ca alloy, the morphology of the primary CaMgSn phase changes from the initial coarse needle-like net to relatively fine short block and/or particle-like shapes. At the same time, the additions of 0.034wt.% or 0.065wt.% Sr suppress the formation of the primary CaMgSn phase, and the addition of 0.10wt.% Sr not only suppresses the formation of the primary and eutectic CaMgSn phases but also promotes the formation of Mg2Ca phase. Furthermore, the addition of minor Sr to the Mg-3Sn-2Ca alloy can improve the tensile properties of the alloy both at room temperature and 150 degrees C. The creep property of the Mg-3Sn-2Ca alloy at 150 degrees C. is also improved by the additions of 0.034wt.% and 0.065wt.% Sr; however, the addition of 0.10wt.% Sr is not beneficial to the creep properties of the Mg-3Sn-2Ca alloy.