The energy of semicoherent interfaces

A model for the energy of a semicoherent interface between two crystal plan es is presented. The interface is decomposed into coherent regions and defe ct regions, such that the defects compensate for the misfit between the two planes. The relaxed energy of the interface - the energy after separation into coherent and defect regions - is given by a weighted average of the en ergy of the individual regions. Thus, given any two crystal structures with arbitrary lattice parameters, one can find the planes and relative rotatio ns that yield good-fitting, low energy interfaces. Calculations are perform ed by varying both the planes comprising the interface and the rotation bet ween them, and computing the associated energy. Results for low energy habi t planes in face centered cubic (FCC)/body centered cubic (BCC) systems mat ch well with experimental data. The results also show that in many, but not all, cases, the optimal relative rotation between planes corresponds to an invariant line orientation. (C) 2000 Elsevier Science Ltd. All rights rese rved.