IV 천이금속 탄화물과 bcc Fe간 계면 에너지의 제일원리 연구

Abstract

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 = Ti, Zr, Hf). The interface energies at relaxed interfaces Fe/TiC, Fe/ZrC, and Fe/HfC were 0.263, 0.153, and 0.271 J/㎡, 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/TiC, Fe/ZrC, and Fe/HfC systems were 0.390, 1.692, and 1.408 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.