Oblique Cube Texture Formation in High Purity Aluminum during Equal Channel Angular Pressing

Aluminum of 5N purity has been deformed at room temperature by equal channel angular pressing using three passes of route A. The microstructure and texture have been investigated by electron back-scattering and neutron diffraction. The microstructure from the first pass on is totally dynamically recrystallized. The recrystallization texture consists of an oblique cube component. The oblate grains and the cube texture are anticlockwise rotated about the transverse direction. The inclination with respect to the extrusion direction depends on the distance from the top of the extruded bar and changes from pass to pass. The mechanism of ormation of the recrystallization microstructure and texture is discussed.

High-strain zones: laboratory perspectives on strain softening during ductile deformation

Deformation in the Earth’s outer shell is mostly localized into narrow high-strain zones. Because they can have displacements up to several hundreds or thousands of kilometres, they can affect the entire lithosphere. The properties of high-strain zones control the kinematics and dynamics of our planet, and are therefore of key importance for an understanding of plate tectonics, stress accumulation and release (e.g. earthquakes), mountain building, etc.

One of the requirements of shear zone formation in ductile rocks is localized strain softening (Hobbs et al. 1990). In this paper we review the strain softening mechanisms that were identified and proposed 25 years ago and analyse their relevance in light of recent experimental results conducted to large strains. For this purpose, some of the newer developments in experimental deformation techniques that permit high strain in torsion are summarized and recent results are reviewed. Using these results we discuss mechanisms, processes and conditions that lead to localization.