About this Abstract |
Meeting |
2020 TMS Annual Meeting & Exhibition
|
Symposium
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Fatigue in Materials: Fundamentals, Multiscale Characterizations and Computational Modeling
|
Presentation Title |
Dislocation Patterns and Crack Initiation in Fatigued Nickel Single Crystal Microcrystals: Micro-Scale In-situ Scanning Electron Experiments |
Author(s) |
Steven Lavenstein, Jaafar A. El-Awady |
On-Site Speaker (Planned) |
Jaafar A. El-Awady |
Abstract Scope |
Here we present a unique approach combining high-frequency fully reversible cyclic uniaxial tension/compression loading in situ scanning electron microscopy experiments on microcrystals fabricated into bulk single crystal nickel. The cyclic loading is imposed using the high frequency actuator dynamics of a nanoindenters. The changes in the dislocation microstructure, and crack initiation and propagation in the microcrystals are monitored by observing changes in the microcrystal dynamic stiffness and SEM imaging. Surface extrusions and TEM characterization confirm the development of persistent slip bands (PSBs) in the microcrystals. However, dislocation vain structures were only observed sporadically, which is markedly different than in bulk crystals. The in situ surface observations, indicate that the PSBs nucleate locally within the crystal interior and then propagate until they spanned the entire slip region. Finally, we quantify crack initiation and propagation in these microcrystals. |
Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |