Papers by Author: Andrzej Piątkowski

Abstract: The local crystallography within shear bands (SB) has been examined in a single crystal of {112}<111> orientation of pure copper deformed at 77K by channel-die compression to strains of about 1. Setting up a system for making high-resolution orientation maps using transmission electron microscopy (TEM) has opened new advantageous circumstances for the analysis of orientation changes within SB. This method with spatial resolution higher than 10nm allows the examination of microstructure images composed of nanoscale subcells forming SB. It has been found that for well-developed shear bands, a crystal lattice rotation about <112> direction tends to dominate and this process is usually accompanied by activation of new slip systems. The present work shows that despite the plane strain deformation mode, the mechanism of lattice rotation within emerging SBs may lead to Goss and Brass texture components.

Abstract: The recrystallization mechanisms in high purity Ag crystals with C{112}<111> initial orientation, deformed by channel-die compression, have been studied by local orientation measurements using TEM and SEM/EBSD. The microtexture analysis clearly indicates the importance of a simple relation of 25-40o (<111> or <112>) type, which is frequently observed during the early stages of recrystallization between isolated nuclei of uniform orientation and one of the as-deformed groups of components. As recrystallization proceeds, recrystallization twinning increases radically. In C-oriented silver single crystals this latter mechanism also plays a decisive role in the formation of the cube orientation.