Microstructure evolution and mechanical properties of Mg-2Y and Mg-2Gd alloys

Pure Mg, Mg-2Y, and Mg-2Gd alloys were fabricated via vacuum melting followed by hot extrusion, and their microstructural evolution and mechanical properties were systematically investigated. The extruded pure Mg and Mg-2Gd alloys exhibited a fully dynamically recrystallized (DRXed) microstructure, whereas the Mg-2Y alloy displayed a bimodal microstructure comprising large elongated grains (LEGs) and fine equiaxed grains (FEGs). Compared to the moderate fiber texture intensity of 5.97 in pure magnesium, the Mg-2Y alloy developed a pronounced < 10–10 > fiber texture associated with the LEGs, reaching a maximum intensity of 13.87. In contrast, the Mg-2Gd alloy exhibited a weak rare-earth (RE) texture with a maximum intensity of just 1.89. Addition of Y significantly enhanced the strength of the magnesium alloy via texture hardening, whereas Gd improved ductility by promoting coordinated deformation within the FEGs. Quasi-in-situ electron backscatter diffraction (EBSD) analysis revealed that the bimodal microstructure in the Mg-2Y alloy underwent recrystallization during annealing. Upon annealing, the < 10–10 > fiber texture in the Mg-2Y alloy was substantially weakened due to the formation of fine grains with random orientations, resulting in a gradual transition toward an RE texture. These findings provide new insights into the microstructural evolution and mechanical behavior of RE-containing Mg alloys . Microstructure of the extruded Mg-2Y alloys after annealing for 15 min: (a) IPF; (b)LEGs; (c) orientations for LEGs; (d)FEGs; (e) orientations for FEGs