Lian, Jie and Wang, Junian and Kim, Yu-Young and Greer, Julia (2009) Sample boundary effect in nanoindentation of nano and microscale surface structures. Journal of the Mechanics and Physics of Solids, 57 (5). pp. 812-827. ISSN 0022-5096 http://resolver.caltech.edu/CaltechAUTHORS:20090904-103700120
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Nanoindentation is a widely used technique to characterize mechanical properties of materials in small volumes. When the sample size is comparable to the indent size, the indentation-induced plastic zone can be affected by the sample boundary which may cause inaccurate interpretation of the mechanical properties. In this study, the sample boundary effect is investigated by performing experiments and atomistic simulations of nanoindentation into nano- and micro-scale Au pillars and bulk Au (0 0 1) surfaces. In experiments, a more compliant deformation is observed in pillar indentations compared to bulk Au. The elastic modulus decreases with increasing indent size over sample size ratio. Atomistic simulations are performed to gain insights on the mechanisms of pillar deformation and pillar boundary effect. The reduced modulus has a similar trend of decrease with increasing indent size over sample size ratio. Significantly different dislocation activities and dislocation interactions with the pillar boundary contribute to the lower value of the reduced modulus in the pillar indentation. The presence of the free surface would allow the dislocations to annihilate, causing a higher plastic recovery during the pillar unloading process.
|Additional Information:||Copyright © 2009 Elsevier. Received 12 December 2007; revised 20 July 2008; accepted 25 January 2009. Available online 30 January 2009.|
|Subject Keywords:||Nanoindentation; Mechanical properties; Sample boundary effect; Dislocations; Atomistic simulations|
|Official Citation:||Jie Lian, Junlan Wang, Yu-Young Kim, Julia Greer, Sample boundary effect in nanoindentation of nano and microscale surface structures, Journal of the Mechanics and Physics of Solids, Volume 57, Issue 5, May 2009, Pages 812-827, ISSN 0022-5096, DOI: 10.1016/j.jmps.2009.01.008. (http://www.sciencedirect.com/science/article/B6TXB-4VGXCYT-1/2/f4d951aa75c1d5d81d7d7f80cd8dca51)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||George Porter|
|Deposited On:||22 Sep 2009 18:02|
|Last Modified:||26 Dec 2012 11:19|
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