Effect of Zn addition on microstructure and mechanical properties of as-cast Mg-2Er alloy

The effect of Zn addition on microstructure and mechanical properties of the Mg-2Er alloy was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the alloys with 1% and 2% Zn (mass fraction) are composed of the W-phase and the α-Mg matrix. Meanwhile, the addition of 4%-10% Zn results in the formation of the I-phase, the W-phase and the α-Mg matrix. When the addition of Zn reaches 12%, the W-phase disappears and the phase constituents of the alloys mainly include the I-phase and the Mg4Zn7 phase besides the α-Mg solid solution. The alloy containing 6% Zn has better mechanical properties, of which the ultimate tensile strength (UTS) and the yield tensile strength (YTS) are about 224 MPa and 134 MPa, respectively, companying an elongation of 10.4%.