Abstract Al diffusion coatings were prepared on g-TiAl alloy by first arc ion plant Al then interdiffusion treatment processes. Al diffusion coatings have a good adherence with the substrate, and EDX and XRD show that the coatings composed of outer thick layer TiAl3 and inner thin layer TiAl2. For g-TiAl without coating under high temperature oxidation at 900oC in air, multilayer oxide scale is formed and consisted of mix of TiO2 and Al2O3, which exhibits relatively poor oxidation resistance. The high temperature oxidation resistance of the specimens coated with Al diffusion coatings is remarkably improved due to the formation of a dense and adherent Al2O3 scale. The oxidation and degradation mechanism of Al diffusion coatings also are discussed.
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