Effect of Nb₂O₅ on Oxidation Behavior of Al₂O₃/TiAl Composites at 900 ℃ in Air

The oxidation behavior of Al2O3/TiAl composites with different Nb2O5 contents prepared by hot-pressing technology were studied at 900 ℃ in air.The results indicated that with the increase of Nb2O5 content the oxidation speed of the composites obviously decreased and the oxidation kinetics obeyed a parabolic law.After oxidation for 120 h,multilayer scales were farmed.The enrichment of Nb in the surface at high temperature could stop the infiltration of oxygen and the outdiffusion of Ti,and thus improve the oxidation resistance of the as-sintered composites.