Local internal stress characterization in a tensile-deformed copper single crystal by convergent-beam electron diffraction

Abstract

Convergent-beam electron diffraction (CBED) was used to measure localized lattice distortions in single-crystal copper deformed in tension. Local lattice parameters were determined by comparison of experimental zone-axis patterns with computer-simulated patterns employing a kinematical approximation. The observed non-cubic distortions are discussed in terms of residual elastic stresses left in the material after external deformation as a result of the formation of a heterogeneous dislocation microstructure. These internal stresses are modelled semiquantitatively using a composite approach, wherein dislocation cell walls constitute a hard phase and dislocation cell interiors a soft phase. The CBED results support the model's predictions of resultant long-range internal stresses that develop as a consequence of maintaining compatibility between the two deforming phases. Aspects of lattice parameter determination with 〈001〉 zone-axis patterns are also discussed.