Deformation microstructures were studied in crystals of high-purity material which had been deformed via multiple slip during channel die compression. The strains ranged up to 1.5; at temperatures ranging from 473 to 773K, and strain rates of between 0.001 and 0.1/s. Four orientations were used; 3 of which corresponded to the stable rolling texture components of polycrystalline face-centered cubic metals. These were C {112}<111>, S {421}<112> and B {110}<112>; and one recrystallization component: {001}<250>. The deformation microstructures were then studied by means of electron back-scattering diffraction and convergent-beam electron diffraction techniques. It was found that the deformation microstructures were sub-divided by dislocation boundaries which demarcated cell blocks that were oriented at between 30 and 55 with respect to the rolling direction. The dislocation boundaries were regularly spaced in 2 groups, which created a regular structure of cell blocks whose size was very strain-rate and temperature dependent. These cell blocks were also characterized by lattice rotations of alternating sign; often about the transverse axis. In all of the crystals, the misorientations between adjacent blocks were of the order of 5 to 10 at a strain of 0.2. At strains which were of the order of unity, some orientations (C, S) developed local regions of very large misorientation. In the case of the B orientation, the misorientations did not exceed 10. Stability of the mosaic dislocation wall pattern was confirmed by post-deformation annealing.

M.C.Theyssier, B.Chenal, J.H.Driver, N.Hansen: Physica Status Solidi A, 1995, 149[1], 367-78