Simultaneous enhancement of strength and ductility by aging treatment in fine-grained Mg-13Gd alloy

Ideal structural materials should have both high strength and good ductility. Aging treatment is an effective way to increase the strength of Mg alloys, but usually sacrifices their ductility. Here we have successfully achieved the synergetic enhancement of strength and ductility of the extruded Mg-13Gd alloy via aging treatment, and obtained a Mg alloy with a tensile yield strength of 400 MPa and an elongation of 15%. The synergetic improvement of strength and ductility is mainly attributed to the formation of high-density nanoscale β′ precipitates and a certain proportion of precipitation free zone in the microstructure dominated by dynamically recrystallized fine grains. The yield drop phenomenon in the tensile curves is sensitive to the existence of movable pinned-dislocations within grains. It is expected that the discussion in this study will be helpful to developing Mg alloys with high strength and ductility via aging treatment.