An Ab Initio Study of Interfacial Energies between Group V Transition Metal Carbides and Bcc Iron

摘要

This paper describes an ab initio study on interface energies, misfit strain energies, and electron structures at coherent interfaces Fe(bcc structure)/MCs(NaCl structure, M = V, Nb, Ta). The interface energies at relaxed interfaces Fe/VC, Fe/NbC, and Fe/TaC were -0.120, -0.169, and -0.158 J/m~2, respectively. It was understood that the dependence of interface energy on the type of carbide was closely related to changes of the binding energies between Fe, M, and C atoms before and after formation of the interfaces Fe/MCs with the help of the NLP/NNBB (Discrete Lattice Plane/ Nearest Neighbour Broken Bond) model and data of the electron structures. The misfit strain energies in Fe/VC, Fe/NbC, and Fe/TaC systems were 0.086, 0.891, and 0.827 eV per 16 atoms(Fe; 8 atoms and MC; 8 atoms). More misfit energy was generated as difference of lattice parameters between the bulk Fe and the bulk MCs increased.