Effect of Microstructure on In Vitro Mechanical Degradation of Extruded Zn–0.4Mg Alloy

Abstract This study examined the influence of microstructure in governing the in vitro mechanical integrity degradation of extruded Zn–0.4Mg (wt pct) alloy by coupling the creep and corrosion responses in simulated physiological environments Two distinct microstructures were produced by extrusion at 150 °C (partially recrystallised microstructure with fine grains) and at 250 °C (fully recrystallised microstructure with coarse grains). The creep tests at the body temperature revealed that, although dislocation creep dominated in both microstructures, creep deformation was accelerated in the 150 °C extruded sample by triggering dynamic recrystallisation. Electrochemical tests indicated that the in vitro corrosion resistance significantly enhanced by increasing grain size and the recrystallisation level. HBSS creep results showed that the 150 °C extruded samples were more vulnerable to failure, because stress-induced cracks tended to initiate at grain boundary regions. The results indicate that, although grain refinement is a common strategy applied for improving static strength, it compromises the in vitro mechanical stability of biodegradable zinc alloys.