Corrosion and Tribocorrosion Behavior of Ti-35Nb-xSn Alloys Manufactured via Electrical Resistance Sintering for Biomedical Use

Ti-35Nb-xSn (x = 0, 4, 6 wt.%) alloys were consolidated by Electrical Resistance Sintering (ERS) at 11 and 12 kA to address the elastic-modulus mismatch and ion-release limitations of Ti-6Al-4V, exploiting the β-stabilizing effect of Nb and oxide-reinforcing effect of Sn. As the corrosion and tribocorrosion behavior of ERS-processed Ti-Nb-Sn alloys has not previously been reported, this study evaluated the combined effect of Sn content and sintering current on static corrosion resistance, tribocorrosion, wear, and ion release in Hartmann–Ringer solution and sulfuric acid. Rietveld refinement revealed a disproportionate increase in α-Ti fraction for the 6 wt.% Sn alloy sintered at 12 kA (41.2 wt.% vs. 29.3 wt.% at 11 kA), coinciding with a shift from smeared, ductile wear debris at 11 kA to coarser, fractured debris at 12 kA, and with an inversion of the sintering-current effect on static corrosion resistance between Sn-free and Sn-containing alloys. The alloy with 6 wt.% Sn sintered at 11 kA showed the best overall performance, combining the highest corrosion resistance, the lowest wear volume loss in sulfuric acid, and stable post-tribocorrosion microhardness, while showing comparable wear resistance to the 4 and 6 wt.% Sn alloys sintered at 12 kA in Hartmann–Ringer solution. Ion release rates remained in the range reported for comparable Ti-Nb-Sn biomedical alloys, supporting the biocompatibility potential of the studied compositions.