DISCLINATION MECHANISM FOR PLASTIC-DEFORMATION OF NANOCRYSTALLINE MATERIALS

A model is developed for the plastic deformation of nanocrystalline ma terials in terms of the evolution of a spatial grid of disclinations l ocated at the triple junctions of grains. Plastic deformation takes pl ace as the result of plastic rotation of grains, the mismatch of whose rotations causes the nucleation of partial disclinations at the junct ions of intergrain boundaries. It is shown that the distinctive featur e of the mechanical behavior of nanocrystals is a deviation from the H all-Petch law up to a critical grain size D-cr less than or equal to 2 5 nm. (C) 1997 American Institute of Physics.