It was noted that disclinations which formed at the junctions of grains during the preparation of ultra fine-grained metals and alloys by severe plastic deformation could make an appreciable contribution to the root mean square elastic strain in as-prepared materials. However, this was less than the contribution which arose from disordered arrays of grain boundary dislocations. It was found that a structural model which was based upon the consideration of random dislocation and disclination ensembles could account for experimental data on internal elastic strains, excess energy and volume expansion in as-prepared ultra fine-grained materials, if high but reasonable values of the grain boundary dislocation densities were assumed. It could therefore be used in theoretical studies of the properties of ultra fine-grained materials that were obtained by using severe plastic deformation techniques.

Random Disclination Ensembles in Ultra Fine-Grained Materials Produced by Severe Plastic Deformation. A.A.Nazarov, A.E.Romanov, R.Z.Valiev: Scripta Materialia, 1996, 34[5], 729-34