The estimation of corrosion behavior of thermal oxidized TiNbTaZr alloys for biomedical applications



The corrosion behavior of two oxidized TiNbTaZr alloys (Ti25Nb8Ta10Zr and Ti21Nb15Ta6Zr) at 500 and 800 °C for 2-h in 0.9 wt% NaCl solution are evaluated. Both samples were examined using electrochemical techniques: electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The electrochemical corrosion parameters obtained from the EIS and potentiodynamic polarization curves indicated a typical passive behavior for untreated and oxidized TiNbTaZr alloys. EIS studies showed high impedance values for both oxidized samples, increasing with exposure time. The polarization results show excellent corrosion resistance for oxidized TiNbTaZr alloys, corroborated by the low corrosion and anodic current density. The oxidation in air at 500 and 800 °C do not exhibit the susceptibility of localized corrosion processes in 0.9 wt% NaCl solution. In addition, scanning electron microscopy (SEM) was employed to observe the surface morphology after polarization test in 0.9 wt% NaCl solution. The oxidized Ti21Nb15Ta6Zr alloy appears to possess superior corrosion resistance than the oxidized Ti25Nb8Ta10Zr alloy in 0.9 wt% NaCl solution.