Excimer laser surface treatment of Ti-6Al-4V alloy and the resulting corrosion properties

Excimer laser surface treatment of Ti-6Al-4V has been carried out with an aim to improve the corrosion resistance of the alloy. Treating the alloy at a laser energy of 5 J/cm2 resulted in the formation of micro-cracks irrespectively to the type of protective gas used, i.e. Ar or N2. Reduced the laser energy to 1.2 J/cm2 has produced crack free surface. The results of both of the open circuit potential measurement and the anodic potentiodynamic polarization test have shown that an improvement in corrosion resistance was obtained when the laser-treated surface is free from micro-cracks, otherwise the reverse is found true. For the former case, the corrosion current density of the Ar-treated specimen could be more than one magnitude of order lower than that of the untreated specimen. The results also show that the corrosion resistance of the N2-treated specimen was slightly inferior to that of the Ar-treated specimen. This is believed to be the result of a more homogenized structure of the latter therefore a better surface passivation was obtained.