The oxidation behavior of Tix(AlCrNb)100-x light-weight medium-entropy alloys in dry air at 600-800 degrees C

Abstract

Air-oxidation behavior of three Tix(AlCrNb)100-x light-weight medium-entropy alloys, where x = 70, 65, and 40, was investigated at 600-800 degrees C. The oxidation kinetics of all alloys obeyed the parabolic-rate law, having the oxidation rates steadily increasing with temperature and Ti content. Intermixed scales of TiO2 and Al2O3 formed on all alloys, and an exclusive TiO2 layer formed in the inner layer and an internal nitrogen attack to form TiN was noted at 800 degrees C. The oxidation mechanism was due mainly to inward oxygen diffusion.