Surface characterization and corrosion resistance of Ti–Al–Zr alloy by niobium ion implantation

The aim of this paper is to study the effect of niobium ion implantation on corrosion resistance and phase formation on the implanted surfaces of Ti–Al–Zr alloy. Niobium ion was implanted into Ti–Al–Zr alloy at energy of 60 keV using a 150 keV accelerator at different fluences ranging from 5 × 1016 to 4 × 1017 ions/cm2, respectively. Electrochemical studies have been conducted in a simulated reactor environment with pH = 10 in order to determine the optimum fluence that can give good corrosion resistance. X-ray photoemission spectroscopy (XPS) and glancing angle X-ray diffraction (GAXRD) were employed to examine the phase formation of niobium ion implanted samples. Niobium implantation into the alloy resulted in precipitation of NbTi4 and Nb precipitates. Microhardness measurements revealed an increase after niobium implantation into the samples. It was found that niobium implantation increases the corrosion resistance. Nature of the surface and reason for the variation and improvement in corrosion resistance are discussed in detail.