Improving the high-temperature oxidation resistance of a beta-gamma TiAl alloy by a Cr(2)AlC coating

A Cr(2)AlC coating was deposited on a beta-gamma TiAl alloy. Isothermal oxidation tests at 700 degrees C and 800 degrees C, and thermocyclic oxidation at 800 degrees C were performed in air. The results indicated that serious oxidation occurred on the bare alloy. Thick non-protective oxide scales consisting of mixed TiO(2) + alpha-Al(2)O(3) 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. (C) 2010 Elsevier Ltd. All rights reserved.