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Emergence of enhanced strengths and Bauschinger effect in conformally passivated copper nanopillars as revealed by dislocation dynamics

Lee, Seok-Woo and Jennings, Andrew T. and Greer, Julia R. (2013) Emergence of enhanced strengths and Bauschinger effect in conformally passivated copper nanopillars as revealed by dislocation dynamics. Acta Materialia, 61 (6). pp. 1872-1885. ISSN 1359-6454. http://resolver.caltech.edu/CaltechAUTHORS:20130424-105427771

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Abstract

The ability to precisely control the surface state of a nanostructure may offer a pathway towards tuning the mechanical properties of small-scale metallic components. In our previous work [Jennings et al., Acta Mater. 60 (2012) 3444–3455], single-crystalline Cu nanopillars were conformally coated with a 5–25 nm thick layer of TiO_2/Al_2O_3. Uniaxial compression tests revealed two key findings associated with these passivated samples: (i) ∼80% higher strengths as compared with the uncoated samples of the same diameter, 200 nm; and (ii) Bauschinger effect-like hysteresis during unloading–reloading segments. Dislocation dynamics simulations of uniaxially compressed 200 nm diameter Cu nanopillars with coated surfaces revealed the contribution of dislocation multiplication, pinning, and pile-up processes to the experimentally observed enhancement in pillar strength. They further helped explain the transition of plasticity mechanisms from dislocation multiplication via the operation of single-arm dislocation sources to dislocation nucleation from the crystal-coating interface. Hysteresis in stress–strain data is discussed in the framework of dislocation structure evolution during unloading–reloading cycles in experiments and simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.actamat.2012.12.008DOIArticle
http://www.sciencedirect.com/science/article/pii/S135964541200866XPublisherArticle
ORCID:
AuthorORCID
Greer, Julia R.0000-0002-9675-1508
Additional Information:© 2012 Acta Materialia Inc. Published by Elsevier Ltd. Received 27 October 2012; received in revised form 6 December 2012; accepted 6 December 2012. Available online 16 January 2013. The authors gratefully acknowledge the financial support of the Kavli Nanoscience Institute (KNI) fellowship and of the W.M. Keck Institute for Space Studies at Caltech. S.W.L. acknowledges the infrastructure and support of the KNI for carrying out the experiments.
Group:Kavli Nanoscience Institute, Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
Kavli Nanoscience Institute UNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
Subject Keywords:Plasticity; Dislocation; Dislocation dynamics; Dislocation density; Coating
Record Number:CaltechAUTHORS:20130424-105427771
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130424-105427771
Official Citation:Seok-Woo Lee, Andrew T. Jennings, Julia R. Greer, Emergence of enhanced strengths and Bauschinger effect in conformally passivated copper nanopillars as revealed by dislocation dynamics, Acta Materialia, Volume 61, Issue 6, April 2013, Pages 1872-1885, ISSN 1359-6454, 10.1016/j.actamat.2012.12.008. (http://www.sciencedirect.com/science/article/pii/S135964541200866X)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38096
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:24 Apr 2013 18:07
Last Modified:09 Sep 2015 23:29

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