Strengthening mechanism and biocompatibility of degradable Zn-Mn alloy with different Mn content

In this study, the mechanical properties and biocompatibility of Zn-Mn alloys with different Mn contents have been investigated. The results show that the grain size of the Zn-Mn alloys decreases with the increasing Mn content and the second phase MnZn 13 precipitates when Mn content is over 0.3 wt%. The elongation increases with the increase of Mn content while Zn-0.3Mn achieves maximum yielding strength and tensile strength ultimate tensile strength. The mechanical properties are dominated by solid solution effect when the Mn content is lower than 0.15 wt% while the effects of grain refinement and precipitation strengthening become remarkable with the Mn content increasing to 0.3 wt%. When the Mn content increases to 0.5 wt%, the tensile strength of the alloy remains unchanged while the elongation is further increased by grain boundary sliding due to further grain refinement and reduced dislocation density. Immersion tests show decreasing Zn 2+ and increasing Mn 2+ concentrations in extract, leading to lower cytotoxicity and better cell proliferation. The Zn-0.5Mn alloy exhibits a maximum comprehensive mechanical property as well as in vitro / in vivo biocompatibility with an implication for biomedical implant applications.