The plastic deformation of nanocrystalline materials was treated here in terms of the evolution of a spatial network of disclinations which were located in the triple junctions of grains. Plastic deformation was then the result of the plastic rotation of grains, the mismatch of which led to the appearance of partial disclinations in joint intergranular boundaries. A process which delayed the increased activity of Frank vectors at the plastic flow stage was a progressive mechanism of dislocation movement; including the emission, absorption and re-emission of dislocations by disclinations. It was shown that an important peculiarity of the mechanical behaviour of nanocrystalline materials was a deviation of the yield stress from the Hall-Petch relationship; up to the critical grain size of 25 to 30nm.

Disclination-Dislocation Model of the Mechanical Behaviour of Crystals Prepared by Crystallization from Amorphous Precursors. S.G.Zaichenko, A.M.Glezer: Materials Science Forum, 1998, 269-272, 687-92