Electrochemical corrosion behaviour of Ti44Ni47Nb9 alloy in simulated body fluids

The anti-corrosion properties of Ti44Ni47Nb9 shape memory alloy in simulated body fluids including 0.9% NaCl, Hankʹs and artificial saliva solutions at pH 2.4, 5.4 and 7.4 are investigated by electrochemical measurements. X-ray photoelectron spectroscopy (XPS) is used to characterize the composition and in-depth distribution of the passive films on the alloy as well as their compositional changes before and after linear polarization measurement with the aim to reveal the corrosion mechanism of the Ti44Ni47Nb9 alloy. The open circuit potential (OCP) increases after adding Nb to TiNi alloy. In 0.9% NaCl solutions, the OCP decreases with increasing pH value and it is contrary for artificial saliva solution. Linear polarization results show that pH values and corrosion solutions have different effect on corrosion behaviour of Ti44Ni47Nb9 alloy. The XPS results verify that after linear polarization the passive film forms on the surface of Ti44Ni47Nb9 consisting of TiO2 and Nb2O5. The experimental results prove that the electrochemical corrosion behaviour of TiNi alloy is improved after adding Nb. This implies that Ti44Ni47Nb9 alloy may be used as a promising implant material.