Enhanced ductility of nanomaterials through optimization of grain boundary sliding and diffusion processes

A theoretical model is which describes the combined effects of grain boundary (GB) sliding and diffusion oil strain hardening and ductility Of nanocrystalline materials (NCMS). Within the model. GB sliding creates disclination dipoles near triple junctions. inducing high elastic stresses and resulting ill pronounced strain hardening. At the same time. GB diffusion partly relieves disclination stresses. thereby decreasing strain hardening. It is theoretically shown that good ductility of NCMs can be reached due to optimizaton of GB sliding, and diffusion processes providing Optimum strain hardening. The latter suppresses plastic strain instability and thus enhances tensile ductility. At the same time. with the optimum strain hardening, the applied stresses reach their critical level at which NCMs fracture only if overall plastic strain is sufficiently large. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.