Internal structures of deformation induced planar dislocation boundaries

The internal structure of planar dislocation boundaries is explored through a coupling of experimental observations of extended geometrically necessary boundaries (GNBs) in deformed single crystals with a dislocation dynamics simulation. The internal dislocation structure of a GNB is approached first through standard diffraction contrast analyses to identify the boundary Burgers vectors in the transmission electron microscope (TEM). This result is placed in the context of a large series of boundaries by the calculation of boundary misorientation angle/axis pairs from Kikuchi pattern analysis in the TEM of orientations on either side of the boundaries. Of special interest are the boundary misorientation axes which together with the boundary normal, allow one to estimate the contribution of primary and secondary dislocations to boundary rotations. Selected boundaries are constructed using the experimental data, crystal plasticity analysis and Frank's formula. The constructed boundaries are input into the dislocation dynamics code and allowed to equilibrate (relax). The internal stress field of the boundary is determined. (C) 2001 Elsevier Science B.V. All rights reserved.