Orientation perturbations near triple junctions in a non-cell forming aluminium-magnesium alloy

The orientation perturbation behaviour near triple junctions in a deformed Al-3wt.%Mg alloy has been investigated using electron back-scatter diffraction by performing line scan measurements both perpendicular and parallel to grain boundaries within a distance of 15 mu m from the triple junction. Crystal orientation map's were also generated to identify local orientation perturbations and to reveal the spatial distribution of domain boundaries. The effect of grain orientation on the degree of perturbation and the presence of grain boundary zones are also investigated. The orientation perturbations followed three characteristic patterns: (i) perturbations were present near the triple junction only; (ii) perturbations were present near the triple junction and within the grain interior and (iii) no perturbations were displayed either near the triple junction or within the grain interior. Enhanced zones of perturbation were also observed near triple junctions, the frequency and magnitude of which increased with strain. There was no apparent relationship between grain orientation and the degree of perturbation although the results did imply that for individual grains, perturbation levels are influenced by the crystallographic orientation of the neighbouring grains. (C) 2000 Elsevier Science S.A. All rights reserved.