The effects of Y on tensile propert

The effects of Y on tensile properties of Mg-5Sn-3Zn alloys are shown in Fig. 9 and Table 3. The results demonstrate these alloys exhibit favorable mechanical properties especially in ductility, and the values are based on the average with an error ratio less than 4%. The ultimate tensile strength(UYS) and elongation(EL) of the ascast alloys first increase and then decrease with the Y addition changes from 0.2 wt% to 0.8 wt%, and the yield strength(YS) almost the same. The maximum UYS and YS are achieved in 0.2%wt Yaddition alloy, valued as 237.1 MPa and 81.6 MPa, respectively, and its elongation reaches to 17.1%. The maximum elongation peaks at 19.2% in the 0.5 wt% Y-addition alloy. Compared to the elongation values of the Mge5Sne3Zn alloy, the Mge5Sne3Zne0.5Y alloy is improved by approximately 36%. But the elongation decreases to 13.8% as the Y addition increases to 0.8 wt% because the massive formed compounds would bring the crack originals. So the Y addition is generally enhancing the properties, but excessive dose of Y, in general, to reduce the elongation. The result is in agreement with the aforementioned images that the favorable properties are achieved in Mg-5Sn-3Zn-0.5Y because of its fine grains and precipitates. However, the hardness(Hv) is not changed notably by the addition of Y.