ELECTROCHEMICAL BEHAVIOR OF NEW BIOCOMPATIBLE TITANIUM ALLOYS CONTAINING Mo, Zr, Ta, AND Nb

Metallic implants operate in a complex physiological environment where electrochemical processes govern corrosion and long-term performance. This work investigates the electrochemical behavior of pure titanium, molybdenum, zirconium, tantalum, and niobium in Ringer’s solution at pH 5.5, using linear polarization, cyclic polarization, and electrochemical impedance spectroscopy (EIS). The results show that titanium and tantalum rapidly form compact and adherent oxide films (TiO₂, Ta₂O₅), which ensure passivation and low corrosion rates. Zirconium exhibits limited passivation with porous oxide layers and mainly generalized corrosion, while molybdenum does not form a stable passive film and corrodes actively, producing weakly adherent porous oxides. Niobium displays intermediate behavior, with partial passivation but reduced stability compared to Ti and Ta. The EIS spectra were adequately fitted using equivalent circuit models with two time constants and constant phase elements. These findings provide a reference framework for understanding the individual role of each element in designing and optimizing future Ti–Mo–Zr–Ta–Nb biomedical alloys.