A method for computing the total strain energy of a dislocation, taking account of both linear and non-linear contributions was applied to a bicrystal. For low values of elastic-moduli mismatch, the dislocation cores were stable, and the results which were obtained using this method were therefore a very reliable basis for deriving a general law for the force on a dislocation in the interface region. The results which were obtained for high values of the elastic moduli-mismatch showed that 2 types of dislocation should be distinguished. One type was those whose core was compact, or slightly extended along several equivalent directions. These could be treated as a perfect dislocation with a constant core width (½<111>-type). The other type included those whose core was likely to dissociate along a preferential direction (not parallel to the interface). These could be considered to be 2 partials which were separated by a planar fault (<001>-type). Upon considering all of the results which were obtained for the first type of dislocation, for 2 different interatomic potentials, it was concluded that the dislocation core-width was the key parameter in a general law. This law did not apply to the second type of dislocation; even for low values of the elastic-moduli mismatch. For such dislocations, the force and core extension could be obtained by resolving 2 non-linear equations; giving the equilibrium of each partial dislocation of mixed character. The present work illustrated a possible, but little-exploited use of atomistic simulations. Although this type of simulation led to a wealth of detail to be understood, it could also be used to derive simple and general laws for immediate application at the mesoscopic scale.

The Image Force on a Dislocation in a Bicrystal - an Atomistic Simulation. J.Lépinoux, P.Beauchamp: Solid State Phenomena, 1998, 59-60, 99-114