Electrochemical corrosion behavior of Ti–24Nb–4Zr–8Sn alloy in a simulated physiological environment

Electrochemical corrosion behavior of a biomedical titanium alloy Ti–24Nb–4Zr–8Sn in weight percent was investigated in a phosphate buffered saline solution at 37 °C utilizing open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Both commercially pure titanium and Ti–6Al–4V alloy were also investigated to make a comparison. The results show that all the samples were spontaneously passivated once immersion into the electrolyte. Ti–24Nb–4Zr–8Sn alloy exhibited a much wider passive region compared with pure titanium and Ti–6Al–4V and also relatively low corrosion current density which is comparable to that of pure titanium in the buffered saline solution, which was attributed to a stable passive film mainly consisted of titanium oxide and niobium oxide on its surface. The EIS results indicated the presence of a single passive layer with thickness ∼2 nm for Ti–24Nb–4Zr–8Sn and pure titanium but a duplex film consisting an inner barrier layer and an outer porous layer on Ti–6Al–4V alloy with thickness of ∼3 nm and ∼2.5 nm, respectively.