Article abstract
Nature Materials 5, 370 - 376 (2006)
doi:10.1038/nmat1632
Subject Categories: Structural materials | Mechanical properties | Surface and thin films
Plasticity, healing and shakedown in sharp-asperity nanoindentation
Graham L. W. Cross1, André Schirmeisen2,3, Peter Grütter4 and Urs T. Dürig5
Abstract
Spatially localized stress fields produced by instrumented, sharp indentation probes are a route to testing the mechanical properties of materials at the smallest length scales. Here we provide direct experimental measurement of indentation plasticity with contact strain fields involving up to a few thousand atoms. We observe two types of nanoscale plasticity: on the pristine surface, high-resolution sensing shows an overall smooth, remarkably reversible indentation response interjected by sudden discrete drops in indenter load. The jumps often occur in pairs with pop-in motion during loading healed by a corresponding pop-out motion on the unload stroke to define a compact hysteresis loop. Despite the general reversibility, cyclic indentation at a single sample position leads to a subtle plastic ratchet and shakedown behaviour with displacements correlated to the underlying gold lattice constant. Our results concur with a previously established picture of thermally activated atomistic plasticity, but suggest a new mechanism at reduced scales that suppresses permanent mass transport.
- SFI Trinity Nanoscience Laboratory, Department of Physics, Trinity College, Dublin 2, Ireland
- Center for Nanotechnology (CeNTech), Gievenbecker Weg 11, 48149 Münster, Germany
-
Physikalisches Institut, Westfälische Wilhelms Universität Münster, Wilhelm-Klemm-Stra
e 10, 48149 Münster, Germany
- Department of Physics, McGill University, 3600 University Street, Montréal, Québec H3A 2T8, Canada
- IBM Research GmbH, Zurich Research Laboratory, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
Correspondence to: Graham L. W. Cross1 e-mail: graham.cross@tcd.ie
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