High-temperature oxidation and its kinetics study of tial and tivalloys in air

Abstract

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 1273K 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 TiV alloys is larger than that of TiAl 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-6 mass%Al alloy according to the results by means of EPMA, although only the rutile Ti-O2 is detected by means of XRD in the oxides of surface layer in Ti6 mass% Al alloy and Ti4 mass%V alloy at 1273 K. Furthermore, the TiO2 and Al 2O3 are observed by XPS in the surface layer of the above both alloys oxidized at 1123K 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. © 2014 The Japan Institute of Light Metals.