During deformation, grain boundaries are properly aligned and slide as groups. When the sliding is blocked by other grains, the local stresses would result in dislocation in the blocking grain, piling up at the opposite grain boundary until the back stress stops further generation of dislocation. The piled up dislocations could climb into and along the grain boundary. Thus, grain-boundary sliding, which is governed by the kinetics of climb along grain boundary to annihilation areas, is feasible due to the constant replacement of the dislocation.
The model elaborates dislocation accommodated sliding mechanism of single grain. Dislocations are generated at scraggy surfaces of grain boundaries. The alignment mechanism of the generated dislocations is the same as that of the Ball–Hutchison model.
Gifkins described grain-boundary sliding and accommodation process as grain-boundary dislocation motion and proposed the core-mantle model. Grain-boundary sliding around grain triple junctions is accommodated by generation of new dislocation and their climbing along the boundaries. Dislocation motion is constrained to occur at grain boundary and mantle area rather than in the core of grain. According to the model, grains are able to slide by switching places in three-dimensional space.
