Stability of eutectic carbide in Fe-Cr-Mo-W-V-C alloy by first-principles calculation

• The bulk properties of the carbides were calculated using first-principles.
• The stability of the γ-Fe/MxC (M = V, W or Mo) interfaces was calculated and analyzed.
• All findings demonstrate that eutectic MC is more stable than M2C, which accords well with the experimental observation.

The structural, electronic and mechanical properties of identified eutectic carbides of the self-designed Fe-Cr-Mo-W-V-C alloy were calculated by first-principles. The interfacial energies of γ-Fe/MxC (M = V, W or Mo) interfaces and the elastic energies were also considered to determine the stability of the carbides. The typical microstructures of this alloy at 1240 °C and 1200 °C were observed. The calculated results show that the formation energies of VC, WC and V2C are all negative, and the absolute value of V2C is the smallest, while that of Mo2C is positive. The density of states (DOS) values of VC and WC at the Fermi level are lower than those of V2C and Mo2C. The elastic constants of VC, WC and V2C are satisfied with their corresponding mechanical stability criteria, instead of Mo2C. The adhesion work Wad of γ-Fe/MC interface model is larger than that of γ-Fe/M2C one, while the interfacial energy of γ-Fe/MC interface model is lower than that of γ-Fe/M2C one. The binding strength of γ-Fe/MC interfaces is larger than that of γ-Fe/M2C ones, while the elastic energy of γ-Fe/MC interface is smaller than that of γ-Fe/M2C one. From first-principles calculations, eutectic MC is more stable than eutectic M2C.

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