High-Temperature Oxidation and Its Kinetics Study of Ti-Al and Ti-V Alloys in Air

The high-temperature oxidation behavior of Ti-(6-36) mass%Al alloys and Ti-(4-15) mass%V alloys has been investigated in a temperature range of 1123 to 1273 K in air. A kinetic study of the oxidation has been also carried out in Ti-6 mass%Al alloy and Ti-4 mass%V alloy. The growth rate of oxides of Ti-V alloys is larger than that of Ti-Al alloys. The oxidation products have been examined by X-ray diffraction (XRD), electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The Al2O3 layer is probably formed in the Ti-Al/oxides interface of the Ti-6mass%Al alloy according to the results by means of EPMA, although only the ruffle TiO2 is detected by means of XRD in the oxides of surface layer in Ti-6 mass% Al alloy and Ti-4 mass%V alloy at 1273 K. Furthermore, the TiO2 and Al2O3 are observed by XPS in the surface layer of the above both alloys oxidized at 1123 K for 3.6 ks, but the V2O5 is not observed. It is found that the apparent activation energy (245 kJ/mol) for the oxidation experiment (TG experiment) at a constant heating rate is fairly equal to the activation energy (253 kJ/mol) for the isothermal oxidation in Ti-6 mass%Al alloys.