Theoretical investigation of moderate misfit and interface energetics in the Fe/VN system

In this study an ab initio based approach to determine the effect of moderate misfit on energies and structures for interfaces is presented and applied to the Fe(0 0 1)/VN(0 0 1) system. The interface energetics of the coherent and semicoherent structures of thin VN films in Fe is investigated in order to determine how the misfit is taken up. The coherent interface is directly treated with ab initio calculations, whereas the semicoherent interface energy is accessed by using a Peierls–Nabarro framework, in which ab initio data for chemical interactions across the interface is combined with a continuum description to account for the elastic distortions. The continuum treatment is here extended to thoroughly account for the anisotropy in the materials. Our approach shows that the elastic contribution to the total interface energy dominates for both the coherent and semicoherent structure and must therefore be accurately accounted for in the interface description. Further, the Peierls–Nabarro framework for the semicoherent interface is evaluated by comparing a full scale two-dimensional solution to one-dimensional approximations. We show that the one-dimensional treatment is sufficient in the present case for accurate results, and consequently interactions at dislocation intersections at the interface do not have to be considered.