Tensile properties of electrodeposited nanocrystalline nickel

For the usage and shaping of engineering parts of nanocrystalline (NC) materials, deformation behavior at both the service temperature and the forming temperature is necessary. For characterization of the mechanical properties of metallic NC materials, NC nickel has been synthesized using electrodeposition processing. In this study, experimental uniaxial tensile testing was performed to elucidate the deformation behavior of NC nickel of 12 nm grain size under various strain rate conditions. In addition to the experimental approach, we provide an account of the mechanical properties of NC nickel materials from our current viewpoint. This is based on recent modeling that appears to provide a conclusive description of the phenomenology and the mechanisms underlying the mechanical properties of NC materials. The experimental results indicate that the deformation in an elastic range is large (similar to 2%) and strain rate insensitive whereas in a plastic deforming range the deformation is small and strain rate sensitive. The fracture strain and stress increases with increasing strain rate. Overall, limited fracture strain results from the absence of strain hardening soon after the elastic limit. Phase mixture modeling could simulate the absence of strain hardening associated with the grain boundary mediated plastic deformation mechanism. (c) 2006 Elsevier B.V. All rights reserved.