Magnesium accounts for about 2.3% o

Magnesium accounts for about 2.3% of the earth's crust surface metal content with its significant advantages of low density, high intensity and stiffness, good damping electromagnetic and shielding performance to get wide attention. Yet the disadvantage of unable to bear high temperature and poor plasticity limits its further application in the industrial field. Currently, the most wide used magnesium alloys contained Al as a major alloying element. However, the Mg-Al based alloys are limited due to the poor reep behavior at elevated temperature which is attributed to the low thermal stability of Mg17Al12 phase [1e3]. Therefore, mprove the microstructure stability become a critical issue for the application of magnesium alloys. Nowadays, Mg-Sn based alloys have used as alternative material for industrial applications. Sn can go into solid solution with Mg and the great performance is attributed to the thermal stability of the Mg2Sn phase [4e7] On the other hand, Zn is considered as a distinguished strengthening element to magnesium alloys since the results demonstrate that Zn addition to the Mg-Sn system results in the grain refinement [8]. Previous researches [9e13] have indicated that the Mg-Sn-Zn alloys exhibit their preferable and possible combination of strength and ductility at room temperature or elevated temperatures and the strengthening mechanism is contacted with the formation of the MgZn2 and Mg2Sn precipitates. Y as one of rare earth elements has been attracted wide attention and used for improve the performance of magnesium alloys. GORNY [10] preliminarily investigated the effect of Y addition on the microstructure of Mg-5Zn-5Sn alloy. They found that Y addition can improve the structural stability of the alloy due to the high temperature ternary phase MgSnY. In this case, combined addition of Sn, Zn and Y to Mg alloys would enhance the performance of wrought Mg alloys. Based on the researches mentioned above, the present work investigated Y-contained Mg-Sn-Zn alloys and the precipitation behavior of second phases in Mg-Sn-Zn-Y alloys is discussed.