The mechanical property improvement of M₇C₃ carbides in hypereutectic Fe–Cr–C hardfacing coating is required for its widespread application and longer service life. Vanadium is a frequently used alloying element, while the effects of V doping on the stability and tensile properties of M₇C₃ carbide have been rarely reported. In this article, the formation enthalpy, structural stability, anisotropic tensile properties and electronic structure of V-doped M₇C₃ (Fe₃Cr₄C₃) carbide were calculated by the first-principles method. The mechanism by which the tensile property of Fe₃Cr₄C₃ carbide can be improved by V-atom doping is discussed. The results show that the formation enthalpy (−0.24 eV/atom) of Fe₃Cr₃VC₃ carbide is lower than that (0.48 eV/atom) of Fe₃Cr₄C₃ carbide, which indicates that the formation of Fe₃Cr₃VC₃ carbide is more facile. The absence of an imaginary frequency in the phonon dispersion spectra reveals that the Fe₃Cr₃VC₃ carbide model is stable. Compared with Fe₃Cr₄C₃ carbide, the tensile strength of Fe₃Cr₃VC₃ carbide in the (0001) crystal face is increased from 44.42 to 48.46 GPa and that in the (1111) crystal face is also increased, from 28.99 to 34.19 GPa. The reasons that the tensile property of Fe₃Cr₄C₃ can be improved by V doping are the electron redistribution and the formation of stronger bonds in Fe₃Cr₃VC₃ carbide.

中文翻译：

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V掺杂对过共晶Fe-Cr-C堆焊层中Fe3Cr4C3碳化物影响的第一性原理研究

M ₇ C ₃碳化物在过共晶Fe-Cr-C堆焊涂层中的力学性能改善是其广泛应用和更长使用寿命的必要条件。钒是一种常用的合金元素，而V掺杂对M ₇ C ₃碳化物的稳定性和拉伸性能的影响鲜有报道。在本文中，V掺杂的M ₇ C ₃ (Fe ₃ Cr ₄ C ₃) 碳化物采用第一性原理计算。讨论了V原子掺杂提高Fe ₃ Cr ₄ C ₃碳化物拉伸性能的机理。结果表明，Fe ₃ Cr ₃ VC ₃碳化物的生成焓（-0.24 eV/atom）低于Fe ₃ Cr ₄ C ₃碳化物的生成焓（0.48 eV/atom），表明Fe ₃ Cr ₃ VC ₃碳化物更容易。声子色散谱中虚频的缺失表明 Fe ₃ Cr ₃ VC₃硬质合金模型稳定。与Fe ₃ Cr ₄ C ₃碳化物相比，Fe ₃ Cr ₃ VC ₃碳化物在(0001)晶面的抗拉强度由44.42 GPa提高到48.46 GPa，在(11 1 1)晶面的抗拉强度也有所提高，从 28.99 到 34.19 GPa。通过V掺杂可以提高Fe ₃ Cr ₄ C ₃拉伸性能的原因是电子重新分布和Fe ₃ Cr ₃ VC ₃碳化物中形成更强的键。