Interfacial Energy of Diffuse Phase Boundaries in the Generalized Broken-Bond Approach

In the present article, the interfacial energy of coherent, planar phase boundaries is treated theoretically in the framework of the generalized n nearest-neighbor broken-bond (NNBB) approach, taking into account that a certain degree of mixing of atoms can occur between the two phases across the phase boundary. This mixing introduces additional entropic contributions to the planar sharp interfacial energy. It is shown that, in this case, the dilute interfacial energy is lower than the energy of the corresponding sharp interface. For the special case of regular solutions, an analytical approximation is developed, which is expressed in relation to the corresponding sharp interface solution. It is shown that the present general broken-bond (GBB) model represents a simple and computationally efficient method for determining diffuse interface energies, particularly in multicomponent systems, where general (e.g., CALPHAD type) thermodynamic data are available.