Microstructure and properties of solution-treated Mg–1.5Zn–0.4Zr–0.5Gd biological magnesium alloys at different extrusion ratios

Abstract

The study investigated the influence of the extrusion ratio on the microstructure, mechanical properties, and corrosion resistance of a Mg–1.5Zn–0.4Zr–0.5Gd bio-magnesium alloy. The results showed that when the extrusion ratio was between 0 and 7.72, the proportion of dynamically recrystallized grains in the alloy gradually increased with an increase in the extrusion ratio, leading to the enhancement of its mechanical properties and corrosion resistance. Beyond an extrusion ratio of 7.72, the alloy underwent complete dynamic recrystallization, and the grain size first increased and finally tended to stabilize with an increase in the extrusion ratio. When the extrusion ratio was between 7.72 and 9.77, with an increase in the extrusion ratio, the continuous increase in the grain size led to a gradual decrease in the mechanical properties of the alloy. At the same time, the reduction in microdefects and improvement of the thermal stability in the alloy gradually enhanced its corrosion resistance. When the extrusion ratio was between 9.77 and 12.76, as the extrusion ratio increased, the dislocation area and density in the alloy gradually rised, leading to an increase in the tensile strength and yield strength, whereas the elongation and corrosion resistance gradually decreased.