| A theoretical model is suggested which describes plastic flow through formation of paired deformation twins at grain boundaries in nanostructured and coarse-grained polycrystalline metallic materials. In the framework of the suggested model, formation and evolution of paired twins at a grain boundary are mediated by successive emission of partial dislocation pairs from this boundary to adjacent grains. It is found that formation of paired deformation twins at grain boundaries can be significantly enhanced due to stress fields created by triple junction disclinations produced by preceding plastic deformation. Energy and stress characteristics of formation of paired twins in nanostructured and coarse-grained polycrystalline metallic materials (Ti, Mg) with hcp lattices are calculated. Results of the suggested theoretical model are consistent with experimental data reported in literature. |
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