Effect of Sr addition on microstructure and elevated temperature mechanical properties of Mg-3Zn-1Y alloy

The effects of Sr addition on the microstructure and elevated temperature mechanical behavior of Mg-3Zn-1Y alloys have been investigated in this research. The results show that α-Mg, W-phase and S-phase are found in the Sr-containing alloys. The S-phase has a higher thermal stability than W-phase, which significantly improves the elevated temperature mechanical properties of the alloy. To further confirm the crystal structure of the S-phase, high resolution transmission electron microscopy analysis was performed and the phase was confirmed to be Mg6Zn2Sr1. With increasing content of Sr, the elevated temperature mechanical properties of the Mg-3Zn-1Y are improved. When the Sr content reached to 0.9 wt%, the alloy shows a much higher ultimate tensile strength of 204 MPa and yield strength of 171 MPa at 250 °C.