IMPROVEMENT IN OXIDATION RESISTANCE OF THE INTERMETALLIC COMPOUND TITANIUM ALUMINIDE BY HEAT-TREATMENT UNDER A LOW PARTIAL-PRESSURE OXYGEN ATMOSPHERE

The improvement in oxidation resistance of an intermetallic compound TiAl was investigated by means of a new type of surface treatment: heat treatment under a low partial pressure oxygen atmosphere. The specimens treated by this method showed superior oxidation resistance compared with a nickel-base superalloy Inconel 713C during cyclic heating to a temperature of 1173 K in static air. The best conditions for the heat treatment under a low partial pressure oxygen atmosphere were found to be: pressure, 6.7 × 10-3Pa; temperature, 1273 K; time, 7.2ks (2h) or more. It was presumed that the excellent oxidation resistance resulting from this method is due to preferential formation of a thin, strong Al2O3 surface layer.