Line defects separating distinct interfacial structures: Topological character and diffusive flux considerations

A rigorous crystallographic framework for the characterisation of interfacial defects which separate (i) crystallographically equivalent and (ii) distinct interfacial structures is described. For this purpose, the Volterra approach for characterising line defects is adapted for bicrystalline media. Defects in the distinct category are described in interfaces of materials with the L1(2) (A(3)B) structure. The diffusive flux of material associated with the motion of such defects is determined and compared with fluxes for defects separating equivalent structures. This is done by modifying a recently developed equation which defines the diffusive flux in terms of the defect's topological parameters. It is shown that grain boundary dislocations in the distinct category with in-plane Burgers vectors may not be glissile but may require diffusive flux for their motion.