Interfacial diffusion aided deformation during nanoindentation
Nanoindentation is commonly used to quantify the mechanical response of material surfaces. Despite its widespread use, a detailed understanding of the deformation mechanisms responsible for plasticity during these experiments has remained elusive. Nanoindentation measurements often show stress values close to a material’s ideal strength which suggests that dislocation nucleation and subsequent dislocation activity dominates the deformation. However, low strain-rate exponents and small activation volumes have also been reported which indicates high temperature sensitivity of the deformation processes. Using an order parameter aided temperature accelerated sampling technique called adiabatic free energy dynamics [J. B. Abrams and M. E. Tuckerman, J. Phys. Chem. B, 112, 15742 (2008)], and molecular dynamics we have probed the diffusive mode of deformation during nanoindentation. Localized processes such as surface vacancy and ad-atom pair formation, vacancy diffusion are found to play an important role during indentation. Furthermore, our analysis suggests a change in the dominant deformation mode from dislocation mediated plasticity to diffusional flow at high temperatures, slow indentation rates and small indenter tip radii.
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physics Div.
- Peking Univ., Beijing (China). BICMR and School of Mathematical Sciences; Princeton Univ., Princeton, NJ (United States). Dept of Mathematics and Program in Applied and Computational Mathematics
- Publication Date:
- OSTI Identifier:
- Report Number(s):
Journal ID: ISSN 2158-3226
- Grant/Contract Number:
- AC52-07NA27344; SC0009248
- Published Article
- Journal Name:
- AIP Advances
- Additional Journal Information:
- Journal Volume: 6; Journal Issue: 7; Journal ID: ISSN 2158-3226
- American Institute of Physics (AIP)
- Research Org:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org:
- Country of Publication:
- United States
- 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; vacancies; hardness; nanotechnology; diffusion; dislocations
Enter terms in the toolbar above to search the full text of this document for pages containing specific keywords.