Revealing the role of Ru in improving corrosion resistance of titanium alloys in HCl solution

The corrosion behaviors of CP Ti, Ti-Ru, Ti-6Al-4V-Ru (Ti-64-Ru) and Ti-5Al-5Mo-5V-1Cr-1Fe-Ru (Ti-55511-Ru) in HCl solution were investigated using open circuit potential, polarization curves, mass loss measurement and X-ray photoelectron spectroscopy. The corrosion current density of Ti-64-Ru was 5 times higher than that of Ti-55511-Ru. While the passive current density of Ti-55511-Ru was higher than that of Ti-64-Ru and a higher corrosion rate was observed in Ti-55511-Ru. Iron oxide was not detected on the Ti-55511-Ru surface. Ru increased the thickness of the passivation film of Ti from ∼49 to ∼208 nm and made it more stable. The effective role of Ru on improving the corrosion resistance of Ti alloys was revealed through direct experimental evidence.