Abstract An investigation based on high-resolution transmission microscopy (HRTEM) and crystallographic analysis was performed to gain insights into vanadium (V) carbide transformations in M23C6 carbide. Vanadium carbides including V6C5, V8C7 and VC were observed in or adjacent to M23C6 carbides, and the orientation relationships for V6C5/M23C6, VC/ M23C6 and V8C7/VC were revealed. Energy dispersive spectrometry (EDS) and atomic-scale configuration analysis on M23C6 contained a certain amount of V indicated that V V atomic pair and local V-rich domain were gradually formed in M23C6 cell as the diffusion of V in M23C6, contributing to formation of vanadium carbides in M23C6. Crystallographic analysis on vanadium carbides observed in M23C6 clarified that the mechanism of vanadium carbide transformations in M23C6 was fulfilled by decreasing of metal atom number in the carbon coordination polyhedron from eight to six, as well that V6C5 and V8C7 containing carbon vacancies precipitated preferentially in M23C6.

中文翻译：

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M23C6碳化物中碳化钒转变的实验观察和晶体分析研究

摘要 为了深入了解 M23C6 碳化物中钒 (V) 碳化物的转变，进行了基于高分辨率透射显微镜 (HRTEM) 和晶体学分析的研究。在 M23C6 碳化物中或附近观察到 V6C5、V8C7 和 VC 等碳化钒，揭示了 V6C5/M23C6、VC/M23C6 和 V8C7/VC 的取向关系。对含有一定量 V 的 M23C6 进行能谱分析 (EDS) 和原子级构型分析表明，随着 V 在 M23C6 中的扩散，VV 原子对和局部富 V 域在 M23C6 细胞中逐渐形成，有助于钒的形成M23C6 中的碳化物。