Oxidation stratification of TiAl based alloy

Interrupted or cyclic oxidation of five TiAl-based alloys at 800 - 1000°C, 100 h were carried out, cross-section microstructure and oxides constitution were investigated by SEM, EDS equipments. The results show that stratification is one of the characteristics of oxidation of TiAl. Mixture layer of TiO₂ + Al₂O₃ is formed firstly, after that there is the formation of diffusion zone inside and pure TiO₂ scale outside. Continuous Al₂O₃ film is observed scarcel. Chemical stratification is transformed into physical stratification once delamination occurs due to the effect of growth stress and thermal stress, and the protection of oxide layers is destroyed consequently.