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Size-induced weakening and grain boundary-assisted deformation in 60 nm grained Ni nanopillars

Jang, Dongchan and Greer, Julia R. (2011) Size-induced weakening and grain boundary-assisted deformation in 60 nm grained Ni nanopillars. Scripta Materialia, 64 (1). pp. 77-80. ISSN 1359-6462. http://resolver.caltech.edu/CaltechAUTHORS:20110321-150812583

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Abstract

Nanocrystalline metals generally exhibit high strengths and good fatigue resistance Their strengthening scales with the inverse of grain size through square root dependence down to grain sizes of ~20 nm, representing the well-known Hall-Petch relation Here we show that in surface-dominated structures with sub-micron dimensions, i e nanopillars, 60 nm grained Ni-W alloys exhibit lower tensile strengths with decreasing pillar diameter, form shear bands and undergo mechanical twinning Moreover, there appears to be a transition in the deformation mechanism from dislocation-driven deformation in pillars with diameters larger than 100 nm to grain-boundary mediated deformation in pillars of 100 nm and below, including grain rotation and grain-boundary migration, processes previously observed only in grain sizes below 20 nm in materials of the same composition We postulate that the presence of free surfaces activates these grain-boundary mediated deformation processes at much larger grain sizes than observed before and results in lower attained strengths.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.scriptamat.2010.09.010DOIArticle
http://www.sciencedirect.com/science/article/pii/S1359646210006184PublisherArticle
ORCID:
AuthorORCID
Greer, Julia R.0000-0002-9675-1508
Additional Information:© 2010 Acta Materialia Inc. Published by Elsevier Ltd. Received 11 August 2010; accepted 8 September 2010. Available online 17 September 2010. The authors gratefully acknowledge the financial support of the National Science Foundation through MRSEC (DMR-0520565) at Caltech and of the Office of Naval Research (grant no. N000140910883), as well as Kavli Nanoscience Institute at Caltech; we thank Prof. C.A. Schuh for providing the bulk samples.
Group:Kavli Nanoscience Institute
Funders:
Funding AgencyGrant Number
NSFDMR-0520565
Office of Naval Research (ONR)N000140910883
Kavli Nanoscience InstituteUNSPECIFIED
Subject Keywords:Mechanical properties testing; Compression test and tension test microscopy and microanalysis techniques; TEM nanocrystalline materials mechanical properties; Twinning microstructure Nanocrystalline microstructure
Record Number:CaltechAUTHORS:20110321-150812583
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110321-150812583
Official Citation:Dongchan Jang, Julia R. Greer, Size-induced weakening and grain boundary-assisted deformation in 60 nm grained Ni nanopillars, Scripta Materialia, Volume 64, Issue 1, January 2011, Pages 77-80, ISSN 1359-6462, DOI: 10.1016/j.scriptamat.2010.09.010. (http://www.sciencedirect.com/science/article/B6TY2-511TNJN-1/2/fa4c6e3069b8be5aa09d26f156569a73)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23017
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Mar 2011 22:21
Last Modified:23 Aug 2016 10:00

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