Abstract: The effect of NiCoCrAlY overlay coatings on the oxidation resistance of γ-TiAl was studied at 900℃ in static air. To hinder the interdiffusion of the elements, the Al/Al₂O₃ layer was added between the coating and the alloy. The results show that the TiAl alloy exhibits poor oxidation resistance. NiCoCrAlY coating can not effectively protect the γ-TiAl substrate from high temperature oxidation because of the serious interdiffusion between the coating and the substrates. With Al/Al₂O₃ diffusion barrier, the NiCoCrAlY coating exhibits excellent oxidation protection on γ-TiAl alloy.

Key words: γ-TiAl; NiCoCrAlY; high temperature oxidation; diffusion barrier