DEFORMATION MICROSTRUCTURE AND ORIENTATION OF FCC CRYSTALS

The effect of crystallographic orientation on the microstructural evolution in f.c.c. metals with medium to high stacking fault energy is analyzed. This analysis is based on a literature review of the behaviour of single crystals and polycrystals supplemented with an experimental study of cold-rolled pure aluminium. It is generally observed that all crystallites subdivide during deformation into cell blocks and cells bounded by rotation dislocation boundaries. In general the boundaries have a macroscopic orientation with respect to the geometry of the specimen. A crystallographic analysis shows that dependent on the crystallographic orientation of the crystal the subdividing boundaries may be nearly parallel to slip planes or they may have a non-crystallographic orientation. This difference is discussed on the basis of an analysis of potential slip planes identified by a Schmid factor analysis.