Crystal lattice rotations induced by twinning and shear banding developed in a Cu–8 at.% Al alloy (representative of face-centered cubic metals with low stacking fault energy) were examined in order to investigate the influence of bands on slip propagation across a structure of twin-matrix layers and the resulting texture evolution. The microstructure and texture of(112)[11¯1] oriented single crystal plane strain compressed up to about 80% at 77K were characterized by transmission electron microscopy including transmission electron microscopic orientation mapping. It was shown that the strong, initial texture changes were due to deformation twinning. Two families of deformation twins, symmetric with respect to the plane perpendicular to the extension direction, were observed. However, only one of them plays a dominant role in strain accommodation. At larger deformations, twin-matrix deflection within some narrow areas leads to kink-type bands, and this was crucial for understanding further texture transformations. The kink bands were precursors of shear bands. It was shown by detailed transmission electron microscopic orientation mapping how the structure of twins and matrix was incorporated into a shear band, and what kind of the dislocation mechanisms were responsible for strain accommodation at the macro-scale. It was found that the re-orientation of the main (111) twinning planes towards the shear band plane facilitated further dislocation slip in the shear direction. Finally, a crystallographic description of shear band formation in completely twinned face-centered cubic metals was proposed based on lattice re-orientations due to localized kinking.

On Twinning and Shear Banding in a Cu–8at%Al Alloy Plane Strain Compressed at 77K. H.Paul, A.Morawiec, J.H.Driver, E.Bouzy: International Journal of Plasticity, 2009, 25[8], 1588-608