Effect of extrusion speed on microstructure and mechanical properties of the Mg-Ca binary alloy

This work reported the effect of extrusion speeds on the microstructures and mechanical properties of Mg-Ca binary alloy. The results showed that yield strength of the as-extruded Mg-1.2 wt.% Ca alloys decrease from similar to 360 MPa to similar to 258 MPa as the ram speed increases from 0.4 mm/s to 2.4 mm/s, and the elongation increases from similar to 3.9% to similar to 12.2%. The microstructure changes from bimodal grain feature to the complete dynamical recrystallization (DRX) with increase of the extrusion speed. The ultrafine DRXed grains in size of similar to 0.85 mu m, the numerous nano-Mg2Ca particles dispersing along the grain boundaries and interiors, as well as the high density of residual dislocations, should account for the high strength. It is believed that the high degree of dynamic recrystallization and the resulting texture randomization play the critical roles in the ductility enhancement of the high-speed extruded Mg alloys. (C) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.