Corrosion behaviour of laser gas nitrided Ti-6Al-4V in HCl solution

Laser surface nitriding of Ti-6Al-4V alloy was carried out with a Nd:YAG pulsed laser. The microstructure and corrosion behaviour of the nitrided samples were examined, using SEM, XRD, XPS, and anodic polarization tests in 2 M HCl solution. Laser nitriding produced a thin continuous TiN layer followed by TiN dendrites and TiN0.3 needles. The laser nitrided specimen exhibited less corrosion current density, passivated more readily and also, maintained a lower current density over the duration of the experiment. This was correlated with the formation of very thin, continuous TiNxOy film, which could retard chloride ions ingress into the substrate. (C) 2009 Elsevier Ltd. All rights reserved.