Pande, Theoretical models of plastic deformation processes

Abstract. We provide an overview of theoretical models of plastic deformation processes in nanocrystalline materials. The special attention is paid to the abnormal Hall-Petch relationship which manifests itself as the softening of nanocrystalline materials with reducing the mean grain size. Theoretical models are considered which describe the deformation behavior of nanocrystalline materials as two-phase composites with grain interiors and boundaries playing the role as component phases. Also, physical mechanisms (lattice dislocation motion, grain boundary sliding, diffusion plasticity mechanisms) of plastic flow in nanocrystalline materials are analysed with emphasis on transitions from one to another deformation mechanism with the reduction of grain size. The effect of a distribution of grain size on the abnormal Hall-Petch relationship in nanocrystalline materials is considered. 1