Journal
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
Volume 60, Issue 1, Pages 84-103Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2011.09.010
Keywords
Microstructures; Dislocations; Nucleation
Funding
- Sandia Corporation (a wholly owned subsidiary of Lockheed Martin Corporation)
- U.S. Department of Energy [DE-AC04-94AL85000]
- National Science Foundation
- NSF [DMR-0748267]
- Los Alamos National Laboratories through LDRD-DR
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [0748267] Funding Source: National Science Foundation
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The strength of true metallic nanowires and nanopillars (diameters below 100 nm) is known to be higher than the strength of bulk metals and is most likely controlled by dislocation nucleation from free surfaces. Dislocation nucleation is a thermally activated process that is sensitive to both temperature and strain rate. However, most simulations rely on high strain rate molecular dynamics to investigate strength and nucleation, which is limited by short molecular dynamics time scales. In this work, the energetics of dislocation nucleation in gold nanowires are computed using atomistic simulations, and transition state theory is used to estimate the strength at experimental strain rates revealing detailed information outside the realm accessible to molecular dynamics simulations. This allows investigation into the competition between thermally activated dislocation nucleation and other failure mechanisms such as elastic and structural instabilities. Additionally, the mechanisms of dislocation nucleation are compared against analytical continuum models which allow a better understanding of the nucleation process including the effects of the wire surfaces. This study helps clarify and consolidate our understanding of the nature of dislocation nucleation in small structures. (C) 2011 Elsevier Ltd. All rights reserved.
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