摘要
The thermal stability and selective nitridation of Cr2AlC under a high-temperature nitrogen atmosphere were studied. Cr2AlC began to decompose beyond 1073 K in N-2, and the activation energy was estimated to be 108.93 kJ.mol(-1). Initially, the selective nitridation led to the generation of an AlN layer, which shielded the underlying Cr2AlC and the process was dominated by a surface reaction. The final products were AlN, Cr7C3 and Cr3C2, and the weaker Cr-Al bonds in Cr2AlC facilitated the rapid diffusion of aluminum from the interior outwards. As the reaction proceeded, micropores were observed on the grain surface, as well as a loose structure, which facilitated the diffusion of N-2 and thus accelerated the reaction. Finally, the intensive reaction involving Cr2AlC and N-2 could be attributed to the gas diffusion channels caused by improved temperature and continuous escape of vaporized aluminum.
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单位东北大学