Oxidation of Cr2AlC at 1300 °C in air

High purity, dense Cr2AlC compounds were synthesized via a powder metallurgical route, and their oxidation behavior was investigated at 1300 °C in air for up to 336 h. A thin external oxide layer formed, which consisted primarily of not Cr2O3 but Al2O3. Since Al was consumed to produce the Al2O3, Al-depletion and Cr-enrichment occurred underneath the Al2O3 layer. This led to the formation of a Cr7C3 layer containing voids. These grew during oxidation, eventually destroying the Cr7C3 layer formed on the unoxidized Cr2AlC matrix.