Mechanical Properties, Corrosion Resistance, and Osteogenic Potential of Novel Biodegradable Mg-Zn-Mn-Ca Alloys

Biodegradable magnesium (Mg)-based materials show promise for orthopedic implants but face challenges such as limited mechanical strength, poor corrosion resistance, and suboptimal biological performance. Alloying offers a practical solution by improving these properties and addressing their rapid degradation in physiological environments. In this study, novel Mg-Zn-Mn-Ca alloys with varying Zn contents were designed, leveraging the biocompatibility of Zn and Ca and the grain refinement effect of Mn. Two compositions, Mg-2Zn-0.5Mn-0.1Ca (wt.%, referred to as Mg2Zn) and Mg-3Zn-0.5Mn-0.1Ca (wt.%, referred to as Mg3Zn), were evaluated for mechanical performance, corrosion resistance, and biological activity to meet the requirements for biodegradable orthopedic implants. Both alloys outperformed pure Mg in mechanical properties. Mg3Zn achieved an ultimate tensile strength of 206.5 MPa and an elongation of 30.1%, demonstrating a balance of strength and ductility. Corrosion resistance analysis showed that Mg3Zn exhibited the lowest corrosion rate (1.17 mm/year) with compact, insoluble corrosion products. In osteogenic potential, Mg2Zn enhanced Runx2 expression 1.69-fold, while Mg3Zn increased Ocn expression 1.95-fold relative to the control, with Mg3Zn consistently showing higher osteogenic capacity. Mg-Zn-Mn-Ca alloys demonstrated sufficient mechanical properties and excellent osteogenic potential, with Mg3Zn outperforming Mg2Zn in corrosion resistance and mid-to-late-stage osteogenesis. These findings position Mg3Zn as a strong candidate for biodegradable metallic orthopedic implants with significant clinical potential.