Local lattice parameter measurements in cyclically deformed copper by convergent-beam electron diffraction

Abstract

Convergent-beam electron diffraction was used to characterize local lattice distortions associated with a heterogeneous dislocation arrangement in cyclically deformed polycrystalline copper. The results indicated the presence of a distorted lattice within the interior of the dislocation cells formed during cyclic deformation. The lattice distortion exhibited a dependence on external deformation conditions. Local lattice parameters were evaluated using computer-simulated patterns based on a kinematical approximation. From these measurements local strains and stresses are estimated. The lattice distortions measured are interpreted in terms of a model predicting substantial long-range internal stresses arising from glide dislocations of opposite sign accumulated on either side of the dislocation cell walls at the interfaces between the walls and the cell interiors.