Laser alloying of Ti-Si compound coating on Ti-6Al-4V alloy for the improvement of bioactivity

Laser alloying of Ti-Si compound coating on Ti-6Al-4V alloy is carried out by a pulsed Nd:YAG laser. The corresponding microstructure, phase structure, microhardness profiles, corrosion properties and bioactivity of the laser-alloyed coatings are investigated to optimize the atomic ratio of Ti-Si. The laser alloyed Ti-Si compound coatings are free of cracks, and primarily present block-like crystals, lath-like crystals and dendrite crystals. The phase structures of both laser-alloyed Ti + Si and 5Ti + 3Si coatings are mainly consisted of α-Ti and Ti5Si3, while the laser-alloyed Si coating is mainly consisted of TiSi2 and Ti5Si3. Microhardness test indicates that the laser-alloyed Si coating has the highest microhardness. Also, corrosion resistance measurement reveals that the corrosion resistance of the laser-alloyed Si coating is much better than that of the Ti-6Al-4V alloy. Evaluation of bioactivity shows that cell growth on the laser-alloyed Si coating with high volume fraction of Ti-Si compounds is faster than that of the Ti-6Al-4V alloy.