About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
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30 Years of Nanoindentation with the Oliver-Pharr Method and Beyond
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Presentation Title |
Nucleation, Activation, and Looking for Perfection: Yield Points in Nanoindentation |
Author(s) |
David F. Bahr, Michael R Maughan, Alexandra C Burch |
On-Site Speaker (Planned) |
David F. Bahr |
Abstract Scope |
Indentation testing of relatively defect free solids can produce yield point discontinuities in nanoindentation load-depth curves. The elastic-plastic transition (pop-in, excursion, load drop, etc.) can indicate either the activation of a pre-existing dislocation source or the nucleation of a dislocation source (which may or may not be itself a dislocation). This presentation addresses extracting information about both the strength and the sub-surface defect density from yield point distributions in metallic and molecular organic materials. Despite order of magnitude differences in mechanical properties, the distribution of yield shows striking similarities, allowing separating measurements that are tied to source activation from those related to dislocation nucleation. This then allows comparisons to computational simulations of “perfect” and defect-containing crystals to be used to validate models needed to predict an array of mechanical deformation mechanisms. |
Proceedings Inclusion? |
Planned: |