Special rotational deformation in nanocrystalline metals and ceramics

A model is suggested which describes a special mechanism for rotational deformation (plastic deformation accompanied by crystal lattice rotation) in nanocrystalline metals and ceramics. Within the model, the special rotational deformation occurs in a nanograin through formation of immobile disclinations whose strengths gradually increase during the formation process as a result of grain boundary sliding and diffusion. The conditions are calculated at which the special rotational deformation is energetically favorable in nanocrystalline Ni, α-Al2O3 (corundum) and TiN-based ceramics.