Microstructure of individual grains in cold-rolled aluminium from orientation inhomogeneities resolved by electron backscattering diffraction

The deformation structure within individual grains of a deformed material is resolved by electron backscattering diffraction. The employed evaluation scheme for local orientation data is illustrated on cold-rolled aluminium. The orientation distribution of each grain is characterized by an averaged orientation spread and its anisotropy; the dependence of both parameters on grain size and grain orientation is discussed. The preferred rotation axis in each grain is determined and shows a dominant orientation spreading around the transversal direction. Characteristic features of the deformation structure (as alternating orientation differences or orientation gradients) are resolved from sign-carrying disorientation angles defined with respect to the preferred rotation axis in each grain. Five components of the dislocation density tensor - corresponding to part of the geometrically necessary dislocation content - are inferred from the local curvatures. The spatially inhomogeneous distribution of the dislocation density offers a new possibility for identifying dislocation boundaries. (C) 2007 Elsevier B.V. All rights reserved.