Application of white x-ray microbeams for the analysis of dislocation structures

The measurement of dislocation structures on mesoscopic length scales is a particularly important application of white-beam Laue microdiffraction. Near a Bragg reflection the intensity distribution in reciprocal space is sensitive to the organization of the dislocations, which occurs at several structural levels. Unpaired geometrically necessary dislocations (GND) and geometrically necessary boundaries (GNB) result in elongated streaks in the Laue image. The direction of the streaks depends on the average orientation of the dislocation arrays and the diffraction vectors. Laue images collected using synchrotron x-ray microbeams are sensitive to the detailed hierarchical distribution of dislocations and can be used to study the orientation and density of individual GNDs and GNBs.