Deformation behaviour of aluminium macrocrystals in the grain boundary region

Abstract

Lattice distortions of deformed aluminium macrocrystals were observed by Electron-microprobe-Kossel techniques. Grain boundary effects due to deformation appeared in various ways such as extraordinary separation and branching of Kossel lines, and as intergranular rotation of the grains in pseudo-Kossel X-ray diffraction patterns obtained from the grain boundary regions of the specimens. Such distortions of the patterns peculiar to the grain boundary regions were attributed to the effect of local slipping induced by the active slip systems of the neighbouring crystals. By the interpretation of these patterns and the orientation relationships between neighbouring grains, it was found that the local slipping was induced towards the slip direction of the active slip plane in the neighbouring crystals, or induced by a type of local stress along the slip direction of the active slip planes in the neighbouring crystals. It was also recognised that at an early stage of stressing, deformation bands were produced in the grain boundary region as a result of a grain boundary effect.