Study on the microstructure and in vitro corrosion behavior of extruded Mg–3Zn–0.7Mn–0.5Sr alloy

Abstract

The susceptibility to corrosion has emerged as a significant barrier to the clinical deployment of magnesium alloys in orthopedic implants. Therefore, in this paper, we elucidate the relationship between the microstructure and corrosion resistance of the as-cast and ER70 Mg–3Zn–0.7Mn–0.5Sr (ZMJ310) alloys, a considerable reduction in the corrosion rate of alloys was observed at large extrusion ratios. The ER70 alloy underwent complete dynamic recrystallization, with the average grain and secondary phase sizes of the alloys refined to 6.5 μm and 1.27 μm. The synergistic impact of grain refinement, optimization of secondary phase distribution and size, grain orientation, and dislocation density significantly, facilitating the formation of denser and more robust protective layer on the ER70 alloy. Concurrently, a reduction in the range of depths of corrosion was observed in the ER70 alloy, with the corrosion depth of ER70 alloys being a mere 6.3% of that observed in as-cast alloy. Furthermore, the release of Zn2+ and Sr2+ in the ER70 alloy is compensated by galvanic corrosion between the Mg14ZnSr phase and the nano Mn particles in its immediate vicinity.

Keywords

• ZMJ310
• Extrusion
• Microstructure
• In vitro corrosion
• Ion release