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 (D0) was 167.2 × 10−4 m2/s.