Seeing is Believing -- Understanding Environmental Degradation and Mechanical Response Using Advanced Characterization Techniques: An SMD Symposium in Honor of Ian M. Robertson: Advanced Characterization I: Transmission Electron Microscopy
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Chemistry and Physics of Materials Committee, TMS: Corrosion and Environmental Effects Committee, TMS: Mechanical Behavior of Materials Committee, TMS: Nuclear Materials Committee
Program Organizers: Kaila Bertsch, Lawrence Livermore National Laboratory; Khalid Hattar, Sandia National Laboratories; Josh Kacher, Georgia Institute of Technology; Bai Cui, University of Nebraska-Lincoln; Benjamin Eftink, Los Alamos National Laboratory; Stephen House, University of Pittsburgh; May Martin, National Institute Of Standards And Technology; Kelly Nygren, Cornell High Energy Synchrotron Source; Blythe Clark, Sandia National Laboratories; Shuai Wang, Southern University of Science and Technology

Monday 2:00 PM
February 28, 2022
Room: 207C
Location: Anaheim Convention Center

Session Chair: Stephen House, University of Pittsburgh/ECC; Khalid Hattar, Sandia National Laboratory; Kelly Nygren, Cornell University/CHESS; Blythe Clark, Sandia National Laboratory

2:00 PM  Invited
Experiments in an Environmental Transmission Electron Microscope: Challenges And Solutions: Renu Sharma1; Wei-Chang Yang1; 1National Institute of Standards and Technology
     Pioneering work on the in situ observation of gas-solid interactions at elevated temperatures, including instrument development, occurred during 1950-1980. In the nineties, the differential pumping system for in situ observation of gas-solid interactions, proposed by Swann and Tighe, was further developed and is now implemented in commercially-available environmental transmission/scanning transmission electron microscopes (ETEM/ESTEM). In recent years ESTEM, has been successfully employed to reveal the structural and chemical changes occurring in nanomaterials in reactive environments. However, quantitative measurements are limited by (a) the nanoscale regions needed for atomic-resolution imaging, (b) uncertainty in the temperature of the imaged region and (c) difficulty in analyzing the large quantities of data.We have addressed these challenges by incorporating Raman spectrometer in ESTEM and developed algorithms for accurate phase identification using FFT, for image drift correction, noise reduction, and peak location to accurate and automatic determinization of the position of atomic columns.

2:30 PM  Invited
Seeing is Believing: Contributions of Advanced Electron Microscopy Techniques to Understanding Materials Degradation in Energy Systems: M Grace Burke1; 1University of Manchester
    As demonstrated extensively by Professor Ian Robertson, advanced electron microscopy techniques – including novel in situ TEM techniques – have played a crucial role in developing our understanding of materials degradation phenomena, such as hydrogen embrittlement, that have impacted the mechanical performance of structural materials. The demanding environments associated with nuclear power systems are particularly detrimental to the performance of structural alloys. Advancements in TEM/STEM instruments coupled with significant improvements in EDXS and EELS, have enabled the identification and characterization of the nanoscale changes in microstructure that are associated with the degradation of mechanical properties. Specifically, special in situ holders now permit materials to be examined in liquids and gases so that localised environmental reactions can be studied in real time in the TEM/STEM. This presentation will highlight the role of advanced AEM in improving the understanding of environment-sensitive degradation phenomena in steels and Ni-base alloys