MICROSTRUCTURE AND LOCAL CRYSTALLOGRAPHY OF COLD-ROLLED ALUMINUM

High-purity aluminium (99.996%) has been deformed by cold-rolling to intermediate reductions (50 and 60%). The microstructure has been characterized using transmission electron microscopy (TEM) and the local crystallographic orientations have been analysed by convergent beam electron diffraction (CBED) using a semi-automatic technique. A number of dislocation configurations such as microbands (MBs), S-bands and lamellar boundaries (LBs) have been characterized in terms of crystallographic 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 combined into orientation images which are related to a framework for the microstructural evolution common to medium and high stacking fault energy f.c.c. polycrystals. This framework consists of a grain subdivision by dislocation boundaries and it is discussed how these boundaries evolve especially how intragranular high angle boundaries can form. The effect of annealing on the deformation microstructure and intragranular nucleation is finally discussed.