An ab initio study of the energetics for interfaces between group V transition metal Nitrides and bcc iron

An ab initio study was carried out on interface energies, misfit strain energies and electron structures at coherent interfaces between bcc Fe and Nitrides (XNs) (NaCl structure, X = V, Nb, Ta). The interface energies at relaxed interfaces Fe/VN, Fe/NbN and Fe/TaN were - 0.051J m(-2), - 0.226J m(-2) and - 0.643 J m(-2), respectively. The influence of bond energy was estimated using the discrete lattice plane/nearest neighbour broken bond model. It was found that the dependence of interface energy on the type of nitride was closely related to changes of the bond energies between Fe, X and N atoms before and after formation of the interfaces Fe/XN. The misfit strain energies in Fe/VN, Fe/NbN and Fe/TaN systems were -0.052, 0.178 and 0.005 eV per 16 atoms ( Fe 8 atoms and XN 8 atoms). The misfit strain energy became larger when the difference in lattice parameters between the bulk Fe and the bulk XNs increased.