Corrosion behaviour of Ti–Nb–Sn shape memory alloys in different simulated body solutions

The corrosion resistance of Ti–Nb–Sn alloys in the 0.9% NaCl physiological and Hankʹs solutions with different pH values (2.4, 5.4, 7.4) at 37 °C were investigated by means of open circuit potential (OCP), Tafel and anodic polarization techniques. The compositions of the passive films were analysed by X-ray photoelectron spectroscopy (XPS). The OCP was found to stabilize within several hours for Ti–Nb–Sn alloys in the Hankʹs solution but continued to increase in the 0.9% NaCl solution. Tafel results indicated that the corrosion current densities were in the magnitude of below 1 μA/cm2. Anodic polarization curves demonstrated a wide passive region. XPS analysis results revealed that the passive film mainly consisted of TiO2, Nb2O5 and SnO2. These observations suggest that Ti–Nb–Sn alloys have a large potential for biomedical applications.