MICROSTRUCTURE AND LOCAL CRYSTALLOGRAPHY OF COLD-ROLLED ALUMINUM

High-purity aluminium (99.996%) has been deformed by cold-rolling to i ntermediate reductions (50 and 60%). The microstructure has been chara cterized using transmission electron microscopy (TEM) and the local cr ystallographic orientations have been analysed by convergent beam elec tron diffraction (CBED) using a semi-automatic technique. A number of dislocation configurations such as microbands (MBs), S-bands and lamel lar boundaries (LBs) have been characterized in terms of crystallograp hic and macroscopic orientations and morphology. For a large number of dislocation boundaries, the angle/axis pairs have been calculated and classified. The microstructural and crystallographic information is c ombined into orientation images which are related to a framework for t he microstructural evolution common to medium and high stacking fault energy f.c.c. polycrystals. This framework consists of a grain subdivi sion by dislocation boundaries and it is discussed how these boundarie s evolve especially how intragranular high angle boundaries can form. The effect of annealing on the deformation microstructure and intragra nular nucleation is finally discussed.