Effect of fine second phase particles on deformation structure in cold rolled copper single crystals

Abstract

<mml:math><mml:mrow><mml:mo>(</mml:mo><mml:mn>111</mml:mn><mml:mo>)</mml:mo><mml:mo>[</mml:mo><mml:mn>1</mml:mn><mml:mover><mml:mn>1</mml:mn><mml:mi>¯</mml:mi></mml:mover><mml:mn>0</mml:mn><mml:mo>]</mml:mo></mml:mrow></mml:math> crystals of pure Cu and Cu–Al₂O₃ (particle size < 200 nm) have been subjected to rolling reductions between 5 and 50%. Through-thickness foils have been examined by high voltage electron microscopy and misorientations measured by scanning transmission electron microscopic microdiffraction. Dislocation cells form at lower strains in Cu–Al₂O₃ than in pure Cu, and they show greater alignment with {111} since the particles prevent relaxation after the load is removed. Although smaller cell sizes occur in the two phase alloys, larger misorientations were found across the cell walls, which indicates that no slip homogenization had occurred. Microbands were found on {111} planes inclined to the rolling plane, but in the two phase crystals they were more prolific. The results are discussed in terms of the effects of the particles on dislocation density and on recovery and relaxation processes.