Laser surface alloying of Ti with Si, Al and Si plus 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 ou t to determine the optimum LSA conditions to form a crack-free and uniform alloyed zone (AZ). Following LSA under such optimum conditions, the kinetic s and mechanism of cyclic oxidation behavior between room temperature and 9 23/1023 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 improv ing oxidation resistance of Ti. This enhanced oxidation resistance has been attributed to the presence of uniformly distributed Ti,Si; in the AZ under neath a SiO2/Al2O3 rich superficial oxide scale. (C) 1999 Elsevier Science S.A. All rights reserved.