High temperature mechanical behavior of an extruded Mg–11Gd–4.5Y–1Nd–1.5Zn–0.5Zr (wt%) alloy

Abstract

The microstructure–property relation of an extruded Mg–11Gd–4.5Y–1Nd–1.5Zn–0.5Zr (wt%) alloy was investigated by conducting hot compression and high temperature creep at temperatures upto 250 °C. The alloy exhibits an average compressive yield strength (σCYSσCYS) of 363±1 MPa and an average elongation to failure (εCFεCF) of 10.5±0.2% at room temperature, 301±13 MPa and 12.8±1.1% at 200 °C. In creep the minimum creep strain rate (View the MathML sourceε̇min) is 1.94×10−9 s−1 at 175 °C/160 MPa and 6.67×10−9 s−1 at 200 °C/100 MPa. The obtained stress exponent n is in the range of 3.7–4.7, suggesting that the creep is controlled by the dislocation climb mechanism. The improvement in compressive strength and creep resistance is attributed to the fine recrystallized grains, SFs in the grain interior, Mg5RE and LPSO phases at grain boundaries. The alloy exhibits a bimodal texture with 〈0001〉 and 〈View the MathML source101¯0〉 components. Its strengthening effect is determined by the competition between these two texture components. In compressive deformation, the textural evolution from 〈View the MathML source101¯0〉 to 〈0001〉 is mainly attributed to the operation of basal 〈a〉 slip and {View the MathML source101¯2}〈View the MathML source101¯1〉 tensile twinning. This texture evolution is not seen in creep.