Effect of Si additions on the mechanical and electrochemical behavior of the as-casted Ti-15Mo alloy in simulated body fluid for biomedical applications.

Titanium (Ti) and its alloys are preferred biomaterials for orthopedic and dental implants due to their excellent biocompatibility and corrosion resistance. However, the development of non-toxic β-Ti alloys with low elastic modulus, high strength, and superior corrosion resistance remains a key challenge for long-term implant applications. The Ti-15Mo alloy is a promising candidate due to its good biocompatibility and mechanical properties. This study investigates the influence of silicon additions (0-2 wt%) on the microstructure, mechanical properties, and corrosion behavior of as-cast Ti-15Mo-xSi alloys for biomedical applications. The corrosion behavior was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) at 37 °C in simulated body fluid (SBF). Moreover, the passive films formed on the surfaces of the alloys were examined using X-ray photoelectron spectroscopy analysis (XPS). The results indicated that Si additions refined the grain size and improved the mechanical properties. All alloys spontaneously formed a stable passive oxide layer. Crucially, the corrosion resistance improved systematically with Si content, as evidenced by a nobler open-circuit potential, a lower corrosion current density (reaching ∼1.03 × 10-7 A cm-2 for the 2 wt% Si alloy), and a higher passive film resistance. XPS confirmed that the passive film is primarily composed of TiO2, with the superior performance of the 2 wt% Si alloy attributed to a denser, more compact oxide layer enriched with protective silicon oxides. The Ti-15Mo-2Si alloy, combining high strength and exceptional corrosion resistance, emerges as a highly promising candidate for load-bearing surgical implants.