Corrosion Behavior of Ti–Nb–Zr–Si Alloy after One-Year Exposure to Simulated Inflammatory Conditions

Abstract Long-term corrosion and elemental release are critical factors controlling the clinical reliability of titanium-based implants, particularly under inflammatory conditions. In this study, commercially pure titanium (CP-Ti), Ti–6Al–4V, and Ti–Nb–Zr–Si (TNZS) alloy were immersed for 372 days under static, non-refreshed conditions in media initially prepared to represent normal, inflammatory, and severe inflammatory environments. After exposure, the specimens were removed, rinsed, and evaluated by open-circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy in freshly prepared solutions of the corresponding nominal compositions. The original immersion solutions were analyzed by inductively coupled plasma optical emission spectrometry to determine released elements. TNZS maintained the most noble electrochemical behavior, lowest corrosion current density, and highest passive-layer resistance in all media. Elemental release increased with solution aggressiveness, following the order normal < inflammatory < severe inflammatory. Ti–6Al–4V released Al and V, whereas TNZS released lower total ion concentrations and avoided potentially harmful alloying elements. Under the tested static, non-refreshed conditions, TNZS showed lower apparent corrosion current density, higher fitted passive-layer resistance, and lower filtered dissolved elemental release than CP-Ti and Ti–6Al–4V.