Microstructure evolution of Cr2AlC MAX phase under a graphite bed between 1100 °C and 1500 °C

作者：Cheng, Yaping; Chen, Junfeng^*; Zhang, Yu^*; Liu, Wenyuan; Nath, Mithun; Wei, Yaowu; Yan, Wen; Zhang, Shaowei; Li, Nan

来源：Ceramics International, 2023, 49(3): 4987-4996.

DOI：10.1016/j.ceramint.2022.10.014

• Cr2AlC MAX
• Oxidation resistance
• Core-shell structure
• Environment corrosion

Thermal decomposition behaviors and microstructure evolution of porous Cr2AlC pellet samples in a graphite bed (65% N-2 and 35% CO) between 1100 degrees C and 1500 degrees C were investigated to explore its potential slag-contact application. A walnut-like structure made of a porous chromium carbides core and Al2O3 shell was confirmed on the original Cr2AlC particle because of the formation of Al-depleted Cr2Al1-xC in the graphite bed atmosphere. After heat treatment at 1300 degrees C, depletion of Al within the Cr2AlC particle caused to generate a similar to 650 mu m thickness CrCx-enriched layer on the sample's surface and a highest Vickers hardness of 13.7 GPa. When the temperature rose to 1500 degrees C, cracks occurred in the sample because of the volumetric expansion from further decomposition. The degradation mechanism of fine-Cr2AlC particles in the range from 1100 degrees C to 1500 degrees C was proposed in detail.

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