Microstructure and mechanical properties of Mg–1.8%Mn alloy modified by single Er and composite Er/Al microalloying

Abstract

Single Er and composite Er/Al additions have been made to Mg–1.8Mn (M2) alloy in order to investigate their influences on the microstructure and resulting mechanical properties of alloy extrusions. Both Er and Er/Al additions suppress the dynamic recrystallization (DRX) during the hot deformation and improve the mechanical properties of the M2 alloy. While single addition of Er significantly suppresses recrystallization and grain growth, composite addition of Er/Al is more effective in grain refinement and microstructural homogeneity of alloy. A versatile mechanical property combination, covering from high plasticity to improved moderate strength, can be achieved by micro alloying. With Er or Er/Al additions, the plasticity substantially increases and generally increases with additional amount. Moreover, composite Er/Al addition is much more effective in improving the plasticity than single Er addition. Comparatively, single Er-containing alloys have considerably higher yield and ultimate strength. Furthermore, deformed microstructures could be preserved in the Er-containing alloys after annealing treatment. The stabilized deformed microstructure is deemed to be the combined effects of the dispersed Mn particles and rare-earth element addition.