Recrystallization nucleation in stable aluminium-base single crystals: Crystallography and mechanisms

Abstract

The predominant crystallographic relations between nuclei and simple deformation structures have been characterized in Al and Al-1%wt.Mn alloy single crystals of stable Goss{011}〈001〉 and brass{110}〈112〉 orientations. Samples were deformed in a channel-die to develop a homogeneous structure comprising two sets of symmetrical microbands and then lightly annealed to 10%–20% recrystallization. SEM/EBSD measurements revealed that the misorientation angles across the recrystallization interfaces are grouped in the range 25–55° (with a maximum at 35–45°) around axes located near, but rarely at, the normals of {111} planes. These misorientations are much higher than those of the as-deformed state. There is also a strong relation between as-deformed orientations and the limited number of recrystallized grain orientations, some of which exhibited growth anisotropy along {111} planes. The results are discussed in terms the creation of twist (low mobility) or tilt (high mobility) grain boundaries of high misorientation by thermally activated, co-ordinated movement of dislocations during recovery. The grain boundaries along which the privileged growth occurs are classified as twist-type since the normal to the boundary plane coincides with the misorientation rotation axis.