Improving Corrosion Resistance, Mechanical Properties and the Biological Performance of a Cast Biodegradable Mg-2ag Alloy by the Addition of Yttrium and Heat Treatment

Biodegradable Mg-Ag alloys are promising implants for bone regeneration owing to their ability to decrease inflammation and infection after implantation by the presence of Ag. However, their bioperformance requires further enhancement. In this regard, the effects of 1 wt% Y addition and solid solution heat treatment (T4) on microstructure, biocorrosion behavior, mechanical properties and biological features of a cast Mg-2Ag alloy were studied. Corrosion tests indicated remarkable role of T4 treatment in promoting corrosion resistance by increasing microstructure homogeneity, reduction of defects and volume fraction of secondary phases as well as eliminating the dendritic microstructure of as-cast Mg-2Ag alloy. The presence of a stable Y-rich corrosion film on the surface of heat-treated Mg-2Ag-1Y alloy could effectively improve the corrosion resistance by inhibiting corrosion propagation. The results of cell culture experiments proved the good cell attachment and proliferation of osteoblast-like cell line MG63 on Mg-2Ag and Mg-2Ag-1Y alloys. Furthermore, the cell attachment and viability were significantly enhanced by the incorporation of Y in the solution state of Mg-2Ag alloy due to the low volume of evolved hydrogen bubbles and superb corrosion resistance