Microstructures and mechanical properties of the age hardened Mg-4.2Y-2.5Nd-1Gd-0.6Zr(WE43)microalloyed with Zn

The effect of trace addition of 0.2 wt.%Zn on the microstructures and mechanical properties of the age-hardening Mg-4.2Y-2.5Nd-1Gd-0.6Zr(wt.%)(WE43)alloy has been investigated.As compared with the WE43 alloy after solid solution treatment at 525 ℃,the block-like Zn-Zr phase was still observed in the WE43-0.2Zn alloy.However,the time for WE43-0.2Zn alloy to get peak hardness at 250 ℃ was two hours,a half earlier than that in WE43 alloy,meaning a accelerated age precipitation kinetics has been achieved due to the addition of 0.2 wt.%Zn.Microalloyed with 0.2 wt.%Zn enhanced the ultimate tensile strength(UTS)slightly and ductility significantly both in the solutionized and peak aged condition.The enhancement in strength and ductility is possible associated with the larger volume fraction of precipitation phases due to a reduction of the solubility of rare earth elements(RE)in theα-Mg matrix,the larger aspect ratio(length to width)of precipitates and a decrease in stacking fault energy by addition of Zn.