The mechanisms of varying doses of metal ion implantation (Ag, Ti and Zr) on microstructure and properties of pure magnesium

Ion implantation technology is a crucial strategy for modulating the degradation behavior of biomedical magnesium alloys. In this study, Ag, Ti, and Zr ions were implanted into the surface of pure Mg at varying doses to investigate their effects on the microstructure and properties of pure Mg. The results revealed that differences in the affinities of Mg and the implanted elements for reacting with oxygen led to the formation of implanted layers with distinct compositions and structures. Specifically, Ag ion implantation resulted in a layer predominantly composed of elemental silver, while Ti and Zr ion implantation promoted the formation of a denser layer containing Mg, MgO, the implanted elements, and their respective oxides. This layer significantly enhanced the corrosion resistance of pure Mg by reducing its susceptibility to corrosive media. Electrochemical assessments showed a substantial reduction in corrosion current density following Ti and Zr ion implantation. However, increasing doses of Ag ions induced heightened susceptibility to galvanic corrosion due to the electrode potential differences between Ag and Mg, thereby accelerating the degradation of the pure Mg substrate. Additionally, first-principles calculations of the work functions for both the (0001) basal plane and the (101¯0) prism plane of Mg corroborated the observed electrochemical trends.