Line Defects Separating Distinct Interfacial Structures: Topological Character and Diffusive Flux Considerations

A rigorous crystallographic framework for the characterisation ofinterfacial defects which separate (i) crystallographicallyequivalent and (ii) distinct interfacial structures is described. Forthis purpose, the Volterra approach for characterising line defectsis adapted for bicrystalline media. Defects in the distinct categoryare described in interfaces of materials with the L1₂(A₃B) structure. The diffusive flux of materialassociated with the motion of such defects is determined and comparedwith fluxes for defects separating equivalent structures. This isdone by modifying a recently developed equation which defines thediffusive flux in terms of the defect's topological parameters. It isshown that grain boundary dislocations in the distinct category within-plane Burgers vectors may not be glissile but may requirediffusive flux for their motion.