Diffusion of oxygen in the Al2O3 oxidation product of TiAl3

The oxidation behavior of TiAl₃ was investigated. The studies were carried out using thermogravimetric analysis (TGA) in the temperature range from 1123 to 1273 K in a 1 atm pure oxygen environment. Samples were analyzed using the X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersion X-ray analysis techniques. The oxidation product was determined to be Al₂O₃ over the temperature range of the investigation. The parabolic-rate constant for TiAl₃ was deduced and compared with those for Ti, TiAl, and Ti₃Al. The electronprobe microanalysis technique was used to obtain concentration profiles for O, Al, and Ti in the oxide layer and the matrix alloy. The parabolic-rate data were used to calculate the diffusivities of oxygen at various temperatures. The activation energy for diffusion was determined to be 337.66 kJ/mol, while the frequency factor (D ₀) was 167.2 × 10⁻⁴ m²/s.