Oxidation of Cr2AlC Between 900 and 1200°C in Air

High-purity, dense Cr2AlC compounds were synthesized by hot pressing a mixture of CrC (X) (x = 0.5) and Al powders. Oxidation at temperatures between 900 and 1200 degrees C in air for up to 480 h resulted in the formation of a thin Al2O3 layer. The consumption of Al to make the Al2O3 layer led to the enrichment of Cr immediately below the Al2O3 layer, resulting in the formation of an underlying Cr7C3 layer. At the same time, carbon escaped from the Cr2AlC into the air. During the initial stage of oxidation, oxygen diffused inward to form the Al2O3 layer, which vastly improved the oxidation resistance of Cr2AlC from the initial stage of oxidation.