When subjected to plastic deformation, grains within ductile face-centred cubic polycrystals fragment into so-called soft low dislocation-density cells separated by so-called hard dislocation-rich walls. Using a narrow-bandwidth, sub-micrometre X-ray beam, the deformation structure inside a single grain within a deformed Ni polycrystal was mapped. Dislocation multiplication and entanglement was found to vary depending upon the physical dimensions of the grain. The method used overcame current limitations of classical X-ray topography and permitted topographic images to be formed from small highly deformed grains.

Mapping the Dislocation Sub-Structure of Deformed Polycrystalline Ni by Scanning Microbeam Diffraction Topography. B.Abbey, F.Hofmann, J.Belnoue, A.Rack, R.Tucoulou, G.Hughes, S.Eve, A.M.Korsunsky: Scripta Materialia, 2011, 64[9], 884-7