Strengthening mechanisms in nanostructured aluminum

Structural parameters that characterize deformation produced nanostructures are the structural morphology, boundary spacing, boundary mis-orientation and interior dislocation density. These parameters have been determined and related to the yield stress of nanostructured Al produced by accumulative roll bonding (ARB) based on mechanisms such as dislocation strengthening and grain boundary strengthening. It has been found that the calculated yield stress is significantly smaller than the experimental value. A supplementary strengthening mechanism has therefore been explored based on the observation of hardening by annealing and softening by slight deformation of ARB samples. (C) 2007 Elsevier B.V. All rights reserved.