Abstract
The industrial applications of Mg alloys are greatly limited by their trade-off of high strength and ductility. In this work, conventional extrusion and rotary swaging (RS) were applied to Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca (wt.%) alloy to obtain high strength-ductility synergy Mg alloys. The microstructure evolution and mechanical properties of as-extruded and as-swaged alloys at different (2, 6 and 10) RS passes were investigated. The results show that large quantity of dislocations occur in twin lamellae and original dynamic recrystallized (DRXed) grains after RS. Those dislocations promote the formation of low-angle grain boundaries (LAGBs) and subgrains. As the RS process continue, these subgrains transform into fine grains with high-angle grain boundaries (HAGBs), which result in grain refinement. Compared to the as-extruded alloys, the strength of as-swaged alloys increases significantly. The edge region of the as-swaged Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca alloy after 10 passes exhibits comprehensive excellent mechanical performance with a yield strength (YS) of 403 MPa, an ultimate tensile strength (UTS) of 427 MPa and a fracture elongation (FE) of 9.1%. The high strength of as-swaged alloys is the results of the combination of dislocation strengthening, fine grain strengthening and dispersion strengthening. The deformed grains deflected to ED and the tensile twins produced during RS enhance the basal texture and reduce the plasticity of the alloy.
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