Ag-enhanced β titanium alloys for surgical implants: microstructural regulation achieves superior strength, corrosion resistance and biocompatibility

β-titanium alloys attract great interest in surgical implants due to its low elastic modulus. The addition of Ag further enhances the strength, ductility, corrosion resistance and biocompatibility of such alloys, which optimizes their compatibility with human bones. In this study, Ti-15Mo-xAg (x = 1, 5 wt.%) alloy rods were prepared by optimized melting, forging and rolling processes. The microstructural evolution, mechanical properties, corrosion behavior and biocompatibility of the alloy were systematically studied by X-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM), mechanical testing, electrochemical analysis and biocompatibility assays. The results showed that the aged Ti-15Mo-5Ag alloy presented a special heterogeneous microstructure of β matrix and micro-nano scale precipitated phase (α1 + α2 + Ti2Ag), which enabled it to achieve excellent mechanical adaptability. Its tensile strength reached 1208 MPa, and the elongation was 11.5%, while the alloy maintained a low elastic modulus of 98 GPa. The self-corrosion current density of the alloy in the simulated body fluids was as low as 1.176 × 10-8 A·cm-2. In vitro biological tests indicated good biocompatibility. This alloy is expected to become a candidate material for future surgical implant applications.