Comparison of as-cast microstructure,tensile and creep properties for Mg-3Sn-1Ca and Mg-3Sn-2Ca magnesium alloys

The as-cast microstructure, tensile and creep properties of Mg-3Sn-1Ca and Mg-3Sn-2Ca magnesium alloys were investigated and compared by using optical microscopy and scanning electron microscopy, X-ray diffraction analysis and tensile tests. The results indicate that the as-cast microstructures of Mg-3Sn-1Ca and Mg-3Sn-2Ca alloys are different. The former is mainly composed of a-Mg, eutectic CaMgSn and solid state precipitation of Mg2Sn, whereas the latter is mainly composed of a-Mg, primary CaMgSn, eutectic CaMgSn and Mg2Ca phases. As a result, the two alloys obtain different tensile and creep properties. Mg-3Sn-1Ca alloy shows relatively higher ultimate tensile strength and elongation at room temperature and 150 ℃ than Mg-3Sn-2Ca alloy, however, the yield strengths of Mg-3Sn-1Ca alloy at room temperature and 150 ℃ are relatively low. In addition, the creep properties of Mg-3Sn-1Ca alloy at 150 ℃ and 70 MPa for 100 h are obviously lower than those of the Mg-3Sn-2Ca alloy.