Improving the high-temperature oxidation resistance of a β–γ TiAl alloy by a Cr2AlC coating

A Cr2AlC coating was deposited on a β–γ TiAl alloy. Isothermal oxidation tests at 700 °C and 800 °C, and thermocyclic oxidation at 800 °C were performed in air. The results indicated that serious oxidation occurred on the bare alloy. Thick non-protective oxide scales consisting of mixed TiO2 + α-Al2O3 layers formed on the alloy surface. The coated specimens exhibited much better oxidation behaviour by forming an Al-rich oxide scale on the coating surface during the initial stages of oxidation. This scale acts as diffusion barrier by effectively blocking the ingress of oxygen, and effectively protects the coated alloys from further oxidation.

Research highlights
► A Cr2AlC coating with pure Cr2AlC MAX phase was deposited on a Ti–Al–V–Mo alloy by using an industrialized magnetron sputtering coater.
► The Ti–Al–V–Mo alloy met severe oxidation attack at 700 °C and 800 °C.
► The Cr2AlC coated specimens exhibited much better oxidation behaviour due to high activity of Al element in the Cr2AlC phase.
► Cr2AlC exhibited significant potential as a protective coating on the Ti–Al–V–Mo alloy.