Disclination densities from EBSD orientation mapping

The aim of the paper is to show experimental evidence of the rotational defects referred to as disclinations in polycrystalline aggregates. Using orientation maps obtained from electron backscattered diffraction or transmission electron microscopy, a method for the recovery of components of the disclination density tensor is presented and applied to various polycrystalline materials. Mapping the disclination densities reveals their extensive presence at intra-granular low-angle boundaries, low and high-angle grain boundaries and triple junctions, irrespective of the material symmetry and grain size. A significant level of rotational incompatibility, with dipolar distribution of the disclinations, is detected in all cases investigated. Since high-angle rotational incompatibility cannot be accounted for consistently by dislocation-based models, the present results support considering disclinations in addition to dislocations in the interpretation of grain boundaries and triple junctions.