Abstract
Nanoscale dislocation loops formed by irradiation can significantly contribute to both irradiation hardening and embrittlement of materials when subjected to extreme nuclear reactor environments. This study explores the application of weak-beam dark-field (WBDF) scanning transmission electron microscopy (STEM) methods for quantitative irradiation-induced defect analysis in crystalline materials, with a specific focus on dislocation loop imaging and analysis. A high-purity Fe-5 wt% Cr model alloy was irradiated with 8 MeV Fe2+ ions at 450°C to a fluence of 8.8 × 1019 m-2, inducing dislocation loops for analysis. While transmission electron microscopy (TEM) has traditionally been the primary tool for dislocation imaging, recent advancements in STEM technology have reignited interest in using STEM for defect imaging. This study introduces and compares three WBDF STEM methods, demonstrating their effectiveness in suppressing background contrasts, isolating defect information for dislocation loop type classification, providing finer dislocation line images for small loop analysis, and presenting inside-outside contrast for identifying loop nature. Experimental findings indicate that WBDF STEM methods surpass traditional TEM approaches, yielding clearer and more detailed images of dislocation loops. The study concludes by discussing the potential applications of WBDF STEM techniques in defect analysis, emphasizing their adaptability across various material systems beyond nuclear materials.
Original language | English |
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Pages (from-to) | 681-691 |
Number of pages | 11 |
Journal | Microscopy and Microanalysis |
Volume | 30 |
Issue number | 4 |
DOIs | |
State | Published - Aug 1 2024 |
Funding
This research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (M.G.B. and Y.-R.L.) and the Fusion Energy Sciences, US Department of Energy (Y.R.L.) under contract DE-AC05-00OR22725 with UT Battelle, LLC. Support was also provided by the Office of Fusion Energy Sciences from grant # DE-SC0023293 with the University of Tennessee (Y.L. and S.J.Z.).
Funders | Funder number |
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Oak Ridge National Laboratory | |
University of Tennessee | |
UT-Battelle | |
U.S. Department of Energy | DE-AC05-00OR22725 |
Fusion Energy Sciences | DE-SC0023293 |
Keywords
- STEM
- TEM
- dislocation
- dislocation loops
- irradiation-induced defects
- weak-beam dark-field