On the interaction of lattice dislocations with grain boundaries

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Abstract
Electron microscope observations of the dissociation of lattice dislocations in a variety of well-defined grain boundaries in thin film bicrystals of gold are described. In addition, previous observations of dissociations are reviewed. It is concluded that all the results can be described formally in terms of dissociations into either perfect, or eventually partial, grain boundary dislocations (GBDs) according to the geometrical theory of crystalline interfaces. A distinguishable perfect GBD is produced whenever a component of the Burgers vector dissociation corresponds to a sufficiently large base vector of the DSC lattice. When the base vectors of the DSC lattice become sufficiently small, the GBDs become indistinguishable by present means of detection. In the limit of vanishingly small base vectors, the formal model of dissociation into indistinguishable GBDs becomes formally equivalent to a uniform core-spreading model, since a uniform spreading can be well represented by a distribution consisting of an infinite number of GBDs possessing infinitesimal Burgers vectors.