Effect of Ag Content and Extrusion on the Microstructure and Mechanical Properties of Mg-Ag Alloys

Recently, the Mg-Ag binary alloy has gained much attention as an antibacterial biomaterial. However, the relationships between the extrusion parameters, microstructure, and mechanical properties of Mg-Ag alloys haven't been clearly established. Therefore, in this paper, the effects of silver (Ag) content (0, 3, 6 wt%) and extrusion (as cast, extrusion ratio (ER) 7.1 and 72.2) on the microstructure and mechanical properties of Mg-Ag alloys are systematically investigated. The results indicate that for the Mg-Ag alloys with the same extrusion ratio, as the Ag increased from 0 to 3 wt%, Mg4Ag and Mg54Ag17 precipitated, leading to significant precipitation strengthening and an increase in the yield strength by over 137%. As the Ag increased to 6 wt%, the yield strength increased by only similar to 20%, attributable to Ag promoting dynamic recrystallization, resulting in less grain refinement, a slower amount increase and a smaller size reduction of the precipitate. For the Mg-Ag alloys with the same Ag content, as the extrusion ratio increased to 7.1, the yield strength increased significantly by over 37%, since the grain boundary strengthening and precipitation strengthening were significantly enhanced as the grains were refined, a large number of precipitates appeared, and their sizes significantly reduced. When the extrusion ratio increased to 72.2, the yield strength increased by only similar to 10%, due to the weakening of both grain boundary strengthening and precipitation strengthening as the recrystallization further improved, leading to an increase in grain sizes, the redissolution of precipitates, and a lesser reduction in their sizes.