Three-Dimensional Porous Ti-15Ta Alloy Surface Dual Passivation Mechanism: Synergy of Alkaline Heat Treatment and Biomineralization

To address the contradiction between mechanical adaptability and biological corrosion in existing titanium alloy implants, this study fabricated Ti-15Ta alloys with macro-micro-nano hierarchical porous structures using polyvinyl alcohol (PVA)-template-assisted powder metallurgy, with titanium and tantalum as raw materials. Alkaline heat treatment and biomineralization were applied to form a dual passivation layer of TiO₂/Ta₂O₅ and hydroxyapatite on the surface. Results showed that the sample with 15 wt% PVA had a porosity of 51.5%, a compressive strength of 151.1 MPa, and an elastic modulus of 18.8 GPa, demonstrating good mechanical matching with cortical bone. After surface modification, the corrosion current density was as low as 5.15×10^-6 A·cm^-2, and the polarization resistance reached 9.2×10³ Ω·cm², representing a decrease in corrosion current density by approximately two orders of magnitude compared to the original sample. The passivation potential range expanded from 0.1 to 1 V, significantly enhancing corrosion resistance. This study proposes a dual-function strategy of "porous mechanical adaptation - dual passivation layer anti-corrosion" to ensure the long-term physiological stability.