Effect of nanocrystalline phase on the electrochemical behavior of the alloy Ti60Ni40

Polarization studies were carried out on crystalline, amorphous and nanocrystalline states of the alloy Ti60Ni40 in 1 M NaCl aqueous medium at room temperature. It was observed that nanocrystalline state exhibits superior corrosion resistance as compared to other states of the alloy Ti60Ni40. Cyclic voltammetry studies and weight loss data corroborates the polarization studies. X-ray photoelectron spectroscopy (XPS) technique was used in order to decipher the nature of the oxide film formed after corrosion test on the specimens of the alloy Ti60Ni40. The crystalline specimen of the alloy Ti60Ni40 shows the presence of Ti2+, Ti3+ and Ti4+ species along with some unoxidized Ti in metallic form (Ti0) whereas the amorphous specimen consists of Ti3+ and Ti4+ species. On the other hand nanocrystalline specimen contains only Ti4+ species. Thus it is likely that the presence of fewer species and the absence of Ti3+ in the oxide film formed on nanocrystalline specimen of Ti60Ni40 lead to the formation of a film with greater homogeneity and protective quality in comparison to the films formed on crystalline and amorphous states of the alloy Ti60Ni40 in 1 M NaCl aqueous medium.

► Polarization studies carried out on different structural states of the alloy Ti60Ni40.
► Nanocrystalline state exhibits superior corrosion resistance as compared to other states of the alloy Ti60Ni40.
► XPS results show that nanocrystalline specimen contains only TiO2 species.
► It leads to the formation of adherent and stable film and improves the corrosion resistance.