Laser surface alloying of Ti with Si, Al and Si+Al for an improved oxidation resistance

This study concerns laser surface alloying (LSA) of Ti with Si, Al or both to enhance the oxidation resistance of pure Ti. A detailed investigation on the effect of process parameters (laser power, interaction time, etc.) on microstructure, composition, phase distribution and hardness was carried out to determine the optimum LSA conditions to form a crack-free and uniform alloyed zone (AZ). Following LSA under such optimum conditions, the kinetics and mechanism of cyclic oxidation behavior between room temperature and 923/1023 K were extensively studied to identify the scope and role of Si and Al in enhancing the oxidation resistance of the substrate. It appears that LSA with Si or Si+Al is more effective than that with Al alone in improving oxidation resistance of Ti. This enhanced oxidation resistance has been attributed to the presence of uniformly distributed Ti5Si3 in the AZ underneath a SiO2/Al2O3 rich superficial oxide scale.