Dislocation generation and displacement in single crystals of a Cu-10.5 at.% Al alloy deformed in bending

Abstract

Single crystals of the Cu-10.5 at.%Al alloy with the [1̄25̄]{12̄1̄}{2̄1̄0} orientation have been deformed by bending about a {12̄1̄} Taylor axis. Narrow slip bands due to activation of the {1̄1̄1}′101̄′ glide system appear on the {2̄1̄0} surfaces at the onset of deformation. These have been studied by optical interference and replica electron microscopy. The corresponding internal dislocation distributions have been studied by etch pitting on {11̄1̄} surfaces. Arrays of edge dislocations with one sign of Burgers vector were observed to extend from the {2̄1̄0} surfaces to the neutral plane on narrow clusters of glide planes. These were formed by sequences of nearly uniformly spaced groups of between 100 and 200 dislocations. The work shows that surface-generated dislocations can be propagated over distances of at least 3.2 mm in these crystals, and excludes the participation of mechanisms depending on the sequential activation of internal sources as an essential feature of the propagation process.