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Imaging Defects and their Dynamics using Scanning Electron Microscopy Approaches

Materials Department, University of California Santa Barbara, USA

The past several years has witnessed a surging popularity of two techniques for defect characterization in crystalline materials: (i) scanning transmission electron microscopy (STEM) using diffraction contrast imaging, and (ii) electron back-scattered diffraction (EBSD) mapping. Here, we link these capabilities by employing a field emission SEM equipped with a transmission detector for defect characterization – termed transmission SEM (TSEM). Imaging modes that are similar to conventional CTEM bright field (BF) and dark field (DF) and STEM are explored, and some of the differences due to the varying accelerating voltages highlighted. We further demonstrate how the richness of information encoded in EBSD patterns is amplified by a new generation of direct electron detectors that enable high speed mapping and acquisition of high-fidelity patterns that can be used for statistically-meaningful defect analyses. We employ these techniques for in situ tensile experiments to study the nature of dislocations dynamics in several structural alloys.

Daniel S. Gianola is a Professor of Materials at the University of California Santa Barbara and can be reached at: gianola@engr.ucsb.edu. He is currently the faculty director of the Microscopy and Microanalysis Facility at UCSB, which is a central shared facility with over 400 active users. Dr. Gianola joined the Materials Department at UCSB in early 2016 after holding the positions of Associate Professor and Skirkanich Assistant Professor, all in the Department of Materials Science and Engineering at the University of Pennsylvania. He received a BS degree from the University of Wisconsin-Madison and his PhD degree from Johns Hopkins University. Prior to joining the University of Pennsylvania, Gianola was an Alexander von Humboldt Postdoctoral Fellow at the Forschungszentrum Karlsruhe (now Karlsruhe Institute of Technology) in Germany. Dr. Gianola is the recipient of the National Science Foundation CAREER, Department of Energy Early Career, and TMS Early Career Faculty Fellow awards. His research group at UCSB specializes in research dealing with deformation at the micro- and nanoscale, particularly using in situ nanomechanical testing techniques.

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