Crystal orientations before and after annealing in an Al single crystal strained in tension

Abstract

A single crystal of initial [10 1 ̄ ] tensile axis orientation was extended 70% in uniaxial tension. The deformed crystal exhibited a macroscopic deformation band structure consisting of deformed matrix bands (DM), domains in which slip occurred predominately on a single slip plane, and special bands of secondary slip (SBSS), which were subdivided into smaller domains in which slip was predominately on one or the other critically stressed slip planes. These slip patterns produce crystal orientations in the deformation structure that are rotated about ±[101] from the initial crystal orientation. After annealing, the SBSS are almost completely recrystallised and the DM are not recrystallised. The recrystallised grains in SBSS have crystal orientations that are rotated in a positive sense about [101] from the initial crystal orientation. The orientations of recrystallised grains in SBSS are near the periphery of the range of orientations found in the deformation microstructure prior to annealing. The orientation and morphology of recrystallised grains in SBSS are consistent with the hypothesis that domains rotated in a positive sense about [101] from the initial crystal orientation have higher stored energy density than domains rotated in a positive sense about −[101]. Recrystallised grains with new orientations were also detected, these have a twin relationship to crystal orientations present in the deformation microstructure; the critically stressed slip planes being twin planes.