Akira Mitsuhashi

High-temperature oxidation process of intermetallic compound Ti-42 at % Al

The oxidation process of two-phase (Ti3Al and TiAl) intermetallic compound, Ti-42 at% Al, in air at 1073 and 1273 K has been investigated. The oxidation at 1273 K is much faster than that at 1073 K; however, the oxidation kinetics are similar. During heating up, TiO2 scale forms initially on the compound surface at about 973 K, and then Al2O3 scale forms at about 1273 K. For the isothermal heating, TiO2 scale slowly grows up at 1073 K, while at 1273 K both TiO2 and Al2O3 scales grow up drastically. The outer oxide scale consists of TiO2 and the inner one consists of a mixture of TiO2 and Al2O3. The volume of Al2O3, which forms after TiO2 formation at the initial stage of oxidation, is larger at an area adjacent to the oxide-compound interface.