A theoretical model was developed, in terms of 2-dimensional dislocation–disclination dynamics, in order to describe the decay of a low-angle tilt boundary in a deformed nanocrystalline material under the action of an externally applied elastic stress and of the elastic field of a neighboring decayed boundary. The critical external stresses were calculated at which the boundary decayed, and at which the dislocations which made up this boundary were either trapped by the boundary that had decayed earlier, or which broke away from both boundaries. The decay of a low-angle tilt boundary was shown to result in a substantial decrease in the critical decay stresses for the neighboring boundaries. This could cause an avalanche-like chain decay of low-angle boundaries, which yielded high-density ensembles of mobile dislocations that were capable of encompassing substantial plastic deformation, and of forming shear bands in deformed nanocrystalline materials.

Chain Decay of Low-Angle Tilt Boundaries in Nanocrystalline Materials. S.V.Bobylev, M.Y.Gutkin, I.A.Ovidko: Physics of the Solid State, 2004, 46[11], 2053-7