Composition and processing effects on the electrochemical characteristics of biomedical titanium alloys

• Ti–13Nb–13Zr alloy and Ti–6Al–4V ELI alloy passivate in Ringer’s solution.
• Passive oxide film of both alloys consists of inner barrier and outer porous layer.
• Experimental EIS data were successfully interpreted by two-layer model.
• The thicker and more porous passive oxide film was formed on the Ti–13Nb–13Zr alloy.
• Superior corrosion resistance is achieved by Ti–6Al–4V ELI alloy water quenching.

The electrochemical behaviour of the Ti–13Nb–13Zr and Ti–6Al–4V ELI alloys with martensitic microstructures was investigated by polarization and electrochemical impedance spectroscopy (EIS) in Ringer’s solution. The impedance spectra were interpreted by a two time-constants equivalent circuit. Both investigated alloys showed high corrosion resistance, but the thin and uniform passive film on the Ti–6Al–4V ELI alloy surface was more protective. The inner barrier and outer porous layer were highly resistant and capacitive. However, thicker and more porous passive film on the Ti–13Nb–13Zr alloy surface may be beneficial for osteointegration. The suitable thermomechanical processing improved the corrosion resistance of Ti–13Nb–13Zr alloy.