“…Fabrication of Si-Al, Al-Y, and Si-Al-Y layers on TiAl alloys have been shown to produce a series of different intermetallic layers (e.g., aluminide and silicide) and oxide layers, increasing the oxidation resistance of the coated alloys [227][228][229][230][231][232]. In particular, J. Xiang et al [232] coated a Ti alloy by means of Si-Y co-deposition and aluminization, which, due to inward diffusion of Al atoms and outward diffusion of Ti and Nb atoms, gave rise to the formation of different mixed intermetallic layers and promoted the preferential development of Al2O3 on the surface in spite of the less resistant TiO2 oxide. In a work by K. Bobzin et al [230], different coatings based on Si-Al and Si-Al-Y were deposited and tested on TiAl, showing an enhanced oxidation resistance thanks to Si and Y addition, promoting the formation of α-Al2O3, YAlO3, and a continuous intermetallic scale of TiSi, with consequent suppression of inward oxidation and outward Ti diffusion.…”