On the structure of grain-boundary dislocations

Applicability of semi-continuum models for the theoretical study of the core structure of grain-boundary dislocations (g.b.d.) is evaluated. It is concluded that these models, although very successful in the case of lattice dislocations, have much less use for g.b.d. and the only meaningful method for the study of the core of these dislocations is atomistic computer simulation. An example of this type of calculation is presented. It is further shown that the conclusions of Gleiter (1977 b) regarding the conditions under which the core spreading of g.b.d. could be expected, are only an artefact of an arbitrary choice of restoring forces, and of the fact that an unstable core was considered in his semi-continuum model. In addition the related experimental evidence for the core spreading is assessed and different interpretations of the experiments are discussed.