Effects of Ga content on the microstructure and mechanical properties of as-extruded Mg-xGa alloys

Microstructures and mechanical properties of the as-extruded Mg-xGa (x = 1, 3, 5, 7 wt%) alloys were investigated in the present work. Examination of as-extruded microstructures revealed that the grains were gradually refined from an average size of 45 µm (Mg-1Ga) to 15.7 µm (Mg-7Ga). Meanwhile, the volume fractions of Mg₅Ga₂ precipitates and dynamic recrystallization grains were significantly increased with increasing Ga content, and the texture was continuously weakened. The grain refinement and texture weakening were mainly ascribed to the increasing dynamic recrystallization stimulated by increasing Mg₅Ga₂ precipitates. The tensile test showed the as-extruded Mg-xGa alloys possessed both high strength and ductility that can meet the mechanical properties required by orthopedic implants. The tensile properties of as-extruded Mg-xGa alloys were gradually increased with increasing Ga content, reaching the highest yield strength of 166 MPa, ultimate tensile strength of 268 MPa, and elongation of 22.2% (Mg-7Ga). The enhanced tensile properties were benefited from a combination of grain refinement strengthening, solid solution strengthening and precipitation strengthening.