Development of the high-strength and corrosion-resistance Mg-Zn-Sn-Ca-Mn alloy for temporary implant applications

The widespread clinical applications of magnesium alloys are currently limited due to the significant challenge of achieving outstanding performance. In this work, a high-performance ZTXM1000 alloy with a bimodal grain structure and a small number of precipitated phases was prepared by the low-alloying composition design together with the low-temperature and slow-speed extrusion processes, and its yield strength and elongation reach 361 MPa and 11.1 %, respectively. The alloy's strengthening mechanism and the dynamic recrystallization mechanism were analyzed. The results demonstrate that fine grain strengthening and work hardening are the primary strengthening mechanisms, while the bimodal grain structure provides excellent coordination of strength and plasticity. In addition, the ZTXM1000 alloy has a lower degradation rate than that of high-purity magnesium, which reaches 0.189 mm/y. The electrochemical and XPS evidence indicate that the surface of the ZTXM1000 alloy establishes a dense quasi-passivated layer with a protective effect under the combined action of oxides and corrosion products in Hank's immersion environment. Results of cellular experiments suggest that the oxides and corrosion products can protect the surface of the ZTXM1000 alloy. The findings of cellular studies demonstrate that the ZTXM1000 alloy has excellent biocompatibility. The activity of co-cultured MC3T3-E1 cells was dramatically boosted in the early stage of live-dead staining tests, which demonstrates that the degradation of ZTXM1000 alloy stimulates the proliferation of MC3T3-E1 cells. Overall, our work successfully prepared a degradable magnesium alloy with outstanding comprehensive performance, which has tremendous potential for orthopedic applications.