Effects of small additions of Zr and Sr on as cast microstructure and tensile properties of Mg–4Y–1·2Mn–0·9Sc (wt-) alloy

The effects of small additions of Zr and Sr on the as cast microstructure and tensile properties of the Mg–4Y–1·2Mn–0·9Sc (wt-) magnesium alloy were investigated. The results indicate that small additions of Zr and/or Sr to the Mg–4Y–1·2Mn–0·9Sc alloy do not cause an obvious change in the morphology and size of the secondary phases. However, the grains of the Zr and/or Sr containing alloys are effectively refined. Among the Zr and/or Sr containing alloys, the grains of the alloy with addition of 0·5 wt-Zr+0·1 wt-Sr are found to be the finest, followed by the alloys with additions of 0·5 wt-Zr and 0·1 wt-Sr respectively. Furthermore, the tensile properties of the Mg–4Y–1·2Mn–0·9Sc alloy, especially the room temperature ductility, are improved by small additions of Zr and/or Sr. Among the Zr and/or Sr containing alloys, the alloy with addition of 0·5 wt-Zr+0·1 wt-Sr obtains the optimum tensile properties at room temperature and 300°C, and the tensile properties of the alloys with additions of 0·5 wt-Zr and 0·1 wt-Sr are similar.