The first-principles and ab initio molecular dynamics simulations revealing the interface energy of the NbC/α-Fe

The low index interfacial configuration, interface energy and electronic properties of NbC/alpha-Fe are calculated using the first-principles method based on density functional theory and ab initio molecular dynamics simulation. Additionally, the NbC/alpha-Fe interface with the low index interfacial configuration is calculated by two-dimensional disregistry method. It is demonstrated that the Fe-C type has an interface energy of -1.553 J/m(2), the smallest interface energy and the most stable structure, therefore the Fe-C type is the most stable conformation of the NbC(001) /alpha-Fe(001). Strong orbital resonance phenomenon exists between Fe-3d, Nb-4d and C-2p, producing strong metallic and covalent bonds. The results of disregistry calculation by different interfacial structures of NbC/alpha-Fe shows that the disregistry of NbC(001)/alpha-Fe(001) crystalline surface is the smallest at 10.19%, which corresponds to the results of interface energy calculation. It can be shown that the alpha-Fe(001) is the optimal orientation surface of the NbC(001) . Herein, we have revealed the site-oriented and stable bonding mode relationship of NbC/alpha-Fe interface in steel, which provides important theoretical guidance to explore the mechanism of grain refinement of NbC particles in shipbuilding steels.