Published online by Cambridge University Press: 26 February 2011
The oxidation resistance of intermetallic compound TiAl was greatly improved in cyclic heating at 900°C by means of a new type of surface treatment, which is the heat treatment under a low partial pressure oxygen atmosphere. The treatment becomes more effective with increasing aluminum content in the specimen. It was presumed that the excellent oxidation resistance resulting from this method is due to preferential formation of a thin and tighit Al2 O3 surface layer, which is formed during the surface treatment at a temperature vicinity of 1000°C and air pressure of about 10−3 Pa. The oxidation resistance of Al2O3 film formed, however, was found to be insufficient at 950°C. A combined treatment consisting of the heat treatment under a low partial pressure oxygen atmosphere followed by a diffusion coating with aluminum showed an excellent resistance to cyclic oxidation even at 950°C.