Application of Weak-Beam Dark-Field STEM for Dislocation Loop Analysis

Yan Ru Lin, Yao Li, Steven J. Zinkle, Jose' D. Arregui-Mena, M. Grace Burke

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

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 languageEnglish
Pages (from-to)681-691
Number of pages11
JournalMicroscopy and Microanalysis
Volume30
Issue number4
Early online dateJul 15 2024
DOIs
StatePublished - Aug 1 2024

Keywords

  • dislocation
  • dislocation loops
  • irradiation-induced defects
  • STEM
  • TEM
  • weak-beam dark-field

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