Corrosion performance and surface analysis of Ti–Ni–Pd–Ru–Cr alloy in nitric acid solution

• Corrosion resistance and surface analysis of Ti based alloys are evaluated.
• The anodic current density decreases with increasing nitric acid concentration.
• XPS studies shows TiO2 and Ti2O3 in both unalloyed Ti and Ti–Ni–Pd–Ru–Cr alloy.
• Corrosion rate of Ti–Ni–Pd–Ru–Cr alloy was considerably lowered than unalloyed Ti.
• The Ti corrosion mechanism and passivity model in nitric acid are described.

The corrosion resistance of Ti–0.4Ni–0.015Pd–0.025Ru–0.14Cr (AKOT Ti) and commercially pure titanium (CP Ti) has been studied in different concentrations of 6, 9 and 11.5 M HNO3, and boiling 15.65 M HNO3. In both CP Ti and AKOT Ti alloy, the open circuit potential and corrosion potential are shifted to more noble potential with increasing concentrations. However, passive current density decreases with increasing concentration. Lower corrosion rate was observed in AKOT Ti (∼0.075 mm/y) compared to CP Ti (∼0.22 mm/y) in boiling 15.65 M HNO3 after 240 h. The mechanisms by which dissolved titanium ions affect the corrosion are also discussed.