High-temperature behaviour of V2AlC powders under nitrogen atmosphere

Abstract

The high-temperature behaviour of V2AlC powders under nitrogen atmosphere was investigated. V2AlC began to react at above 1073 K under nitrogen, and the activation energy was calculated to be 435.42 kJ·mol−1. In the initial stage, the thermal decomposition was controlled by a surface reaction and the formation of nitride layers could inhibit further nitridation, and the final products were AlN, VCx, V(C, N)x, and VN. As the reactions proceeded, the generated nitrides and carbides caused a volume change and cracked the resulting layers, which could promote the diffusion of nitrogen and accelerate the decomposition of V2AlC. As a result, the intensive reaction above 1473 K between V2AlC and nitrogen was attributed to crack propagation and the opening of gas diffusion channels generated by the increasing temperature and persistent escape of vaporised Al.