Effect of replacement of V by Fe and Nb on passive film behavior of Ti-6Al-4V in simulated body fluid conditions

The effect of replacing V in the alloy Ti-6Al-4V by Fe and Nb on the electrochemical behavior in simulated body fluid conditions has been addressed in the present study. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to study the passivation behavior of Ti alloys (Ti-6Al-4V, Ti-6Al-4Fe and Ti-6Al-4Nb) as a function of immersion time in Hank's solution. The Fe and Nb containing alloys exhibited higher passive film resistance after immersion in Hank's solution as compared to Ti-6Al-4V alloy. The mechanical behavior of cast Ti-6Al-4Fe and Ti-6Al-4Nb was also evaluated. The cast Ti-6Al-4Nb alloy exhibited improved ductility compared to Ti-6Al-4Fe alloy. The fracture mode in Ti-6Al-4Fe was essentially brittle while Ti-6Al-4Nb exhibited mixed mode failure.