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Plasticity, healing and shakedown in sharp-asperity nanoindentation.
Graham L W Cross1, André Schirmeisen, Peter Grütter
1SFI Trinity Nanoscience Laboratory, Department of Physics, Trinity College, Dublin 2, Ireland. graham.cross@tcd.ie
Nature Materials
|April 18, 2006
Summary
This study reveals nanoscale plasticity in materials using sharp indentation. We observed reversible responses with discrete load drops, suggesting a new mechanism suppressing permanent mass transport at reduced scales.
Area of Science:
- Materials Science
- Nanotechnology
- Mechanical Engineering
Background:
- Instrumented sharp indentation probes enable testing of mechanical properties at small length scales.
- Understanding nanoscale plasticity is crucial for designing advanced materials.
Purpose of the Study:
- To experimentally measure indentation plasticity and contact strain fields at the atomic scale.
- To investigate the mechanisms of nanoscale plasticity and their reversibility.
Main Methods:
- Utilizing high-resolution sensing to measure contact strain fields involving thousands of atoms.
- Performing cyclic indentation at single sample positions to observe plastic behavior.
Main Results:
- Observed two types of nanoscale plasticity: reversible indentation with discrete load drops (pop-ins/pop-outs).
- Identified subtle plastic ratchet and shakedown behavior correlated with the gold lattice constant.
- Demonstrated a new mechanism at reduced scales that suppresses permanent mass transport.
Conclusions:
- Results align with thermally activated atomistic plasticity but propose a novel mechanism at reduced scales.
- The observed phenomena offer new insights into material deformation at the nanoscale.
- This research contributes to the fundamental understanding of mechanical behavior in nanomaterials.