Surface-porous Ti-10Nb alloy with bone-like modulus and antibacterial activity via high-temperature Ag diffusion

To address the problems of stress shielding and premature implant failure in orthopedic applications, this study presents a surface-porous Ti-Nb-Ag alloy with a bone-matching elastic modulus, fabricated via Ag high-temperature diffusion and vacuum removal strategy. The fabrication process involved electroplating Ag onto Ti-xNb (x = 0, 10, 50 wt%) substrates, followed by high-temperature vacuum heat treatment (1100 °C and 5 ×10⁻⁴ Pa) to engineer porous surface. The porous Ti-Nb-Ag structure forms through Ag sublimation, a peritectic reverse reaction, and Ti phase reorganization under high-temperature vacuum conditions. As a β-phase stabilizing element, Nb inhibits the grain boundary diffusion of Ag by changing its segregation behavior at different temperatures. The local elastic modulus of the surface pores on the Ti-10Nb-Ag alloy is 43.4 ± 2.3 GPa, primarily attributed to its high porosity (41 % porosity, average pore size of 3.62 μm). The electrochemical measurements in simulated body fluid (SBF) revealed that the porous Ti-10Nb-Ag exhibited a corrosion rate (I_corr = 41.71 μA/cm²) higher than that of dense Ti (I_corr = 1.38 μA/cm²), primarily due to the enhanced cathodic activity from residual Ag. Furthermore, after 7 d of culture, MG-63 cell viability remained above 80 %, indicating that the porous Ti-10Nb-Ag exhibits excellent biocompatibility. And achieved 100 % antibacterial efficacy against Staphylococcus aureus(S. aureus) within 48 h via sustained Ag⁺ release. These findings underscore the surface-porous Ti-Nb-Ag alloys exhibit potential applications in biomedicine.