Water vapor oxidation behavior and mechanism of high-entropy (TiZrNbTaCr)C at 1200°C

Abstract

High-entropy (TiZrNbTaCr)C ceramics with different Cr content were oxidized at 1200°C in water vapor. Zr6(Nb, Ta)2O17, (Nb, Ta)2O5 and (Ti, Nb, Ta, Cr)O2 were initial oxidation products. After a 4-h oxidation, TiO2-(Nb, Ta)2O5 was produced and changed from Ti(Nb, Ta)2O7 to Ti2(Nb, Ta)10O29 with increasing Cr content, resulting in better oxidation resistance. TiO2-(Nb, Ta)2O5 with large size and relatively dense microstructure impeded the inward diffusion of water vapor, slowing down the oxidation rate and causing the change of oxidation kinetics from linear to parabolic. The formation process of the oxide scale was discussed and the corrosion mechanism was proposed.