TEM study of the early stages of Ti2AlC oxidation at 900 °C

The cross-sectional microstructure on Ti2AlC oxidized for 1 h at 900 °C was investigated using focused ion beam/transmission electron microscopy. An Al-depleted intermediate layer formed between the oxide scale and the substrate that consisted of nonstoichiometric Ti2AlxC nanocrystallites. The oxide scale consisted of a TiO2-rich outer layer and an Al2O3-rich inner layer. Ti2AlC has been theoretically predicted to preserve its crystal structure down to a sub-stoichiometry of Ti2Al0.5C, and such a Ti2AlxC phase was observed in this study.