Changes in the five-parameter grain boundary character distribution in α-brass brought about by iterative thermomechanical processing

Abstract

This paper analyzes the changes in the five-parameter grain boundary character distribution in α-brass brought about by iterative thermomechanical processing (ITMP). In both reference and ITMP specimens, there was a tendency for boundaries to terminate on {1 1 1} planes. The high incidence of coherent twins and other boundaries terminated on {1 1 1} planes led to a high concentration of asymmetric tilt boundaries with 〈1 1 0〉 misorientations. After ITMP there was a larger population of coherent twins, an increase in the number fraction of Σ9 and Σ27 boundaries, an increase in the fraction of boundaries terminated on {1 1 1} planes (even when Σ3 boundaries are excluded), a decrease in the number of triple junctions with three random boundaries, and an increase in the number of triple junctions with three twin-related boundaries. The results add strength to the suggestion that ‘special’ boundaries are those that terminate on low-index planes.