Two conditions under which image forces became significant were when a dislocation was close to a surface (or interface) or when the dislocation was in a nanocrystal. This investigation pertains to the calculation of image forces under these circumstances. A simple edge dislocation was simulated using finite element method by feeding-in the appropriate stress-free strains in idealised domains, corresponding to the introduction of an extra half-plane of atoms. Following basic validation of the new model, the energy of the system as a function of the position of the simulated dislocation was plotted and the gradient of the curve gave the image force. The reduction in energy of the system arose from two aspects: firstly, due to the position of the dislocation in the domain and, secondly, due to deformations to the domain (/surfaces). The second aspect became important when the dislocation was positioned near a free-surface or in nanocrystals and could be calculated using the current methodology without constructing fictitious images. It was to be noted that domain deformations were ignored in the standard theories for the calculation of image forces and, hence, they gave erroneous results (magnitude and/or direction) whenever image forces played an important role. An important point to be noted was that, under certain circumstances, where domain deformations occurred in the presence of an edge dislocation, the ‘image' could be negative (attractive), zero or even positive (repulsive). The current model was extended to calculate image forces based upon the usual concept of an image dislocation.

Image Forces on Edge Dislocations: a Revisit of the Fundamental Concept with Special Regard to Nanocrystals. P.Khanikar, A.Kumar, A.Subramaniam: Philosophical Magazine, 2011, 91[5], 730-50