Effect of Ce addition on the oxidation behaviour of Mo–Si–B–Al ultrafine composites at 1100 °C

Mo73.4Si11.2B8.1Al7.3Mo73.4Si11.2B8.1Al7.3 ultrafine eutectic–dendrite composites undergo severe oxidation at 1100 °C in dry air, being transformed completely into mullite and cristobalite. However, the net mass loss is reduced by at least ∼40%∼40% during 24 h exposure upon minor Ce addition to the alloy, indicating an unusual improvement in oxidation resistance. The presence of Ce hinders mullatization, and leads to the formation of a protective Si–O-rich layer in the scale. The relationship between oxide scale composition and the oxidation kinetics has been examined.