Effects of trace Ag on precipitation behavior and mechanical properties of extruded Mg-Gd-Y-Zr alloys

The effects of trace Ag element on the precipitation behaviors and mechanical properties of the Mg-7.5Gd-1.5Y-0.4Zr (wt.%) alloy by means of tensile test, X-ray diffractometry, scanning electron microscopy, electron backscattered diffractometry, and scanning transmission electron microscopy. There is an unusual texture (< 0001 >//extrusion direction) in the extruded Mg-Gd-Y-Zr alloys containing 0.5 wt.% Ag. During the aging periods at 225 degrees C, the addition of the trace Ag does not form new precipitates, just accelerates aging kinetics, and refines beta' precipitates, thereby increasing the number density of the beta' precipitates by Ag-clusters. Moreover, the Mg-Gd-Y-Zr alloy containing 0.5 wt.% Ag shows the most excellent synergy of strength and plasticity (408 MPa of ultimate tensile strength, 265 MPa of yield strength, and 12.9% of elongation to failure) after peak-aging.