Shear banding and recrystallization nucleation in a Cu–2%Al alloy single crystal

Abstract High-purity Cu–2%Al single crystals with initial C{112}〈111〉 orientation have been deformed by channel-die compression at 77 and 293 K to develop fine shear bands in a twin-matrix (T-M) substructure. The microstructural and microtextural changes during deformation and the early stages of recrystallization have been studied in detail by TEM/CBED and SEM/EBSD. Local orientations measurements indicate that the scattering of the original T-M orientations within shear bands towards two, twin-related positions is due to the localised lattice rotation around the TD ‖ 〈011〉 axis. The starting points for the occurrence of new, recrystallized grains are the {110}〈100〉 and {114}〈221〉 components of the as-deformed microtexture inside the shear bands. As recovery and recrystallization proceed, the orientations of the primary nuclei systematically evolve to adopt simple boundary misorientation relations of ∼30°〈111〉 type with respect to one of the two components of the deformed matrix. The results of the present study clarify the respective roles of all three basic mechanisms, i.e. oriented nucleation, growth (defined here as ∼30°〈111〉) and recrystallization twinning which are involved in the initial stages of recrystallization texture development in this low stacking fault energy alloy.