Microstructural evolution and mechanical properties of Mg–11Gd–4.5Y–1Nd–1.5Zn–0.5Zr alloy prepared via pre-ageing and hot extrusion.

The Mg–11Gd–4.5Y–1Nd–1.5Zn–0.5Zr (wt%) alloy was pre-aged prior to hot extrusion. Pre-ageing treatment introduced uniform distribution of plate-like Mg 5 RE precipitates, which transformed into nano-scale globular Mg 5 RE particles by split and spheroidization during hot extrusion. These globular Mg 5 RE particles contributed to continuous dynamic recrystallization by promoting the evolution of low misorientation sub-grain boundaries to high misorientation grain boundaries and caused grain refinement through grain boundary pinning. The improved mechanical properties were ascribed to the grain refinement, globular Mg 5 RE and LPSO precipitates. The ratio of compressive to tensile yield strength is 1.2. The yield strength asymmetry was attributed to the deformation asymmetry of LPSO phase and non-isotropic deformation behaviors of Mg matrix in tension and compression. [ABSTRACT FROM AUTHOR]