The generation and propagation of misorientation bands in polycrystalline metals under large deformations were theoretically investigated. Disclination models were used to describe the generation of misorientation bands at grain boundary kinks and junctions.

These models considered edge disclination dipole and quadrupole configurations, and predicted the value of the critical external shear stress, τg, above which the nucleation of misorientation bands occurred. Numerical estimates led to τg-values of G/1000 to G/400, where G was the shear modulus. These corresponded to the levels of deforming stress observed in materials with a fine grain structure. The critical stress was shown to be strongly dependent upon the geometries and strengths of initial disclinations at grain-boundary faults. Further development of the disclination structure at an isolated grain boundary fault led to 2 main regimes of misorientation-band development. These were stable and unstable propagation. The transition between the 2 regimes was controlled by another critical value for external stress which was several times higher than τg. Computer simulations of dislocation-disclination interactions were also performed by using 2-dimensional dislocation-disclination dynamics.

Disclination Models of Misorientation Band Generation and Propagation. M.Y.Gutkin, K.N.Mikaelyan, A.E.Romanov, P.Klimanek: Physica Status Solidi A, 2002, 193[1], 35-52