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Dislocation Confinement and Ultimate Strength in Nanoscale Polycrystals

Published online by Cambridge University Press:  01 February 2011

Qizhen Li
Affiliation:
Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, U.S.A.
Peter M. Anderson
Affiliation:
Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, U.S.A.
Michael Mills
Affiliation:
Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, U.S.A.
Peter Hazzledine
Affiliation:
Universal Energy Systems Inc., Dayton, OH 45432, USA
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Abstract

Nanoscale polycrystalline metals typically exhibit increasing hardness with decreasing grain size down to a critical value on the order of 5 to 30 nm. Below this, a plateau or decrease is often observed. Similar observations are made for nanoscale multilayer thin films. There, TEM observations and modeling suggest that the hardness peak may be associated with the inability of interfaces to contain dislocations within individual nanoscale layers. This manuscript pursues the same concept for nanoscale polycrystalline metals via an analytic study of dislocation nucleation and motion within a regular 2D hexagonal array of grains. The model predicts a hardness peak and loss of dislocation confinement in the 5 to 30 nm grain size regime, but only if the nature of dislocation interaction with grain boundaries changes in the nanoscale regime.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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