First-principles investigation of V-doping effects on Fe₃Cr₄C₃ carbide in hypereutectic Fe–Cr–C hardfacing coating

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.

Computing details

(I)

Crystal data

P1	α = 90°
a = 7.04567 Å	β = 90°
b = 7.04567 Å	γ = 120°
c = 4.28278 Å

Data collection

h = →	l = →
k = →

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Biso*/Beq
C1	0.186313	0.813687	0.554074	1.000000*
C2	0.186313	0.372626	0.554074	1.000000*
C3	0.627374	0.813687	0.554074	1.000000*
C4	0.813687	0.186313	0.054074	1.000000*
C5	0.813687	0.627374	0.054074	1.000000*
C6	0.372626	0.186313	0.054074	1.000000*
Cr1	0.128787	0.871212	0.005654	1.000000*
Cr2	0.128788	0.257575	0.005654	1.000000*
Cr3	0.742425	0.871212	0.005654	1.000000*
Cr4	0.871212	0.128788	0.505654	1.000000*
Cr5	0.871212	0.742425	0.505654	1.000000*
Cr6	0.257575	0.128787	0.505654	1.000000*
Fe1	0.457110	0.542890	0.335111	1.000000*
Fe2	0.457110	0.914221	0.335111	1.000000*
Fe3	0.085779	0.542890	0.335111	1.000000*
Fe4	0.542890	0.457110	0.835111	1.000000*
Fe5	0.542890	0.085779	0.835111	1.000000*
Fe6	0.914221	0.457110	0.835111	1.000000*
V1	0.333333	0.666667	0.780774	1.000000*
V2	0.666667	0.333333	0.327473	1.000000*