About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
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| Symposium
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Four-Dimensional Scanning Transmission Electron Microscopy (4D STEM) for Quantitative Materials Characterization
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| Presentation Title |
Extracting Hidden Signals in 4D STEM: Spatial and Temporal Fluctuations in Complex Materials |
| Author(s) |
Po-Cheng Kung, Scott Dahl, Rui Feng, Peter K. Liaw, Jian-Min Zuo, Jessica Krogstad, Paul M. Voyles |
| On-Site Speaker (Planned) |
Po-Cheng Kung |
| Abstract Scope |
Complex materials inherently produce complex electron-diffraction patterns, where weak signals of interest from nanoscale features are obscured by the bulk matrix background. Using 4D STEM, we can isolate these hidden, weak signals to study nanoscale structural and chemical fluctuations. Here, we focus on two primary examples: spatial chemical fluctuations in medium-entropy alloys (MEAs), and temporal structural fluctuations in metallic supercooled liquids (SCLs) and glasses. First, by decoupling weak superlattice signals from the scattering background, we observed the transition from directionally, partially ordered chemical short-to-medium-range ordering (S/MRO) to full L12 long-range ordering in a CrCoNi-based MEA. Second, isolating time-fluctuating speckles allows for tracking individual structural S/MRO domains over time. This approach directly probes structural relaxation dynamics, revealing spatially heterogeneous and facilitated dynamics in PdCuSi-based metallic SCLs and glasses. Together, these approaches illustrate the generalizable capability of 4D STEM to decode complex phenomena across diverse material systems. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Characterization, High-Entropy Alloys, Other |