Effects of Ce, Y and Gd additions on as-cast microstructure and mechanical properties of Mg-3Sn-2Sr magnesium alloy

The effects of Ce, Y and Gd additions on the as-cast microstructure and mechanical properties of Mg-3Sn-2Sr alloy were investigated and compared by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry analysis, tensile and creep tests. The results indicate that the Mg-3Sn-2Sr ternary alloy is mainly composed of α-Mg, primary and eutectic SrMgSn, and Mg2Sn phases. After the additions of 1.0% Ce, 1.0% Y and 1.0% Gd to the Mg-3Sn-2Sr alloy, the Mg12Ce, YMgSn, GdMgSn and/or Mg17Sr2 phases are formed, respectively. At the same time, the formation of the primary SrMgSn phase is suppressed and the coarse needle-like primary SrMgSn phase is modified and refined. In addition, the additions of 1.0% Ce, 1.0% Y and 1.0% Gd to the Mg-3Sn-2Sr alloy can simultaneously improve the tensile and creep properties of the alloy. Among the Ce-, Y- and Gd-containing alloys, the tensile properties of the Ce-containing alloy are relatively higher than those of the Y- and Gd-containing alloys.