Understanding pop-ins in spherical nanoindentation
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Empa, Swiss Federal Laboratory for Materials Testing and Research (Switzerland)
- Georgia Institute of Technology, Atlanta, GA (United States)
In this study, pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interrupted spherical indentation tests along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- W911NF-10-1-0409; AC52-06NA52396; Center for Integrated Nanotechnologies; Los Alamos National Laboratory Director�??s Postdoctoral Fellowship
- OSTI ID:
- 1227459
- Alternate ID(s):
- OSTI ID: 1224247
- Report Number(s):
- LA-UR-14-27887; APPLAB
- Journal Information:
- Applied Physics Letters, Vol. 105, Issue 16; ISSN 0003-6951
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols
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journal | December 2019 |
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