Unraveling the Dose-Dependent Effects of Fe and Zn Implantation on Regulating the Surface-to-Interface Degradation Process of Magnesium

Magnesium-based biodegradable implants exhibit significant potential due to their biocompatibility and suitable mechanical properties; however, their rapid corrosion remains a major limitation for clinical applications. Surface modification via ion implantation offers a promising approach to enhance performance; however, the specific effects and mechanisms of iron and zinc implantation require further elucidation. In this study, Fe and Zn were implanted into the surface of pure magnesium using metal vapor vacuum arc technology to enhance its corrosion resistance, mechanical properties, and biocompatibility. The study revealed that low-dose Fe implantation increased polarization resistance (<i>R</i>_p) to approximately 2.08 × 10³ Ω cm², whereas high-dose Zn implantation achieved 2.13 × 10⁴ Ω cm², reducing degradation rates to 21.67 and 3.29 mm y^-1, respectively. Fe implantation strengthened the material via dislocation formation and lattice distortion, increasing the hardness by 157%, whereas Zn implantation formed a dense ZnO/MgO film, reduced the carrier concentration, and improved the hardness by 141%, thereby effectively stabilizing the corrosion process. As a result, the corrosion mechanism shifted from hydrogen evolution-dominated in pure Mg to pitting in Fe-implanted samples and more uniform corrosion in Zn-implanted samples. Moreover, both treatments significantly promoted cell proliferation and reduced cytotoxicity. These findings elucidated the multiscale mechanisms of ion-implanted magnesium-based materials and provided quantitative guidance for the design of high-performance biodegradable Mg implants.