Ultraviolet laser surface treatment for biomedical applications of β titanium alloys:: morphological and structural characterization

To improve the surface properties of beta titanium alloys developed for biomedical applications we have recently suggested a methodology involving laser-assisted nanostructuration. This strategy would benefit from superficial laser heat treatment since laser annealing displays many advantages as compared to the conventional methods: high resolution, high operating speed, low cost and retaining the initial bulk properties. Therefore, this paper reports results concerning the laser treatment of beta titanium alloys under vacuum. Our interest has been focused on the excimer laser single-pulse irradiation (lambda = 248 nm) of a model beta titanium alloy (Ti-6.8Mo-4.5Fe-1.5Al). The threshold laser fluences corresponding to beta transus, melting and ablation temperatures as well as the resulting modification depth were first approached theoretically. KIF laser annealings were then carried out in vacuum, varying the fluence conditions from submelting heating to ablation regimes. Subsequent atomic force microscopy and scanning electron microscopy observations were performed to follow the structural and topographical modifications of as-treated specimens and were then discussed as regards the above-mentioned theoretical parameters.