Methods, Techniques, and Materials Discovery of Irradiation Effect Using In-situ Microscopy: Advances in Microstructure Characterization and Data Analysis
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee, TMS: Advanced Characterization, Testing, and Simulation Committee
Program Organizers: Wei-Ying Chen, Argonne National Laboratory; Xuan Zhang, Argonne National Laboratory; Kevin Field, University of Michigan; Donald Brown, Los Alamos National Laboratory; Aida Amroussia, GE Global Research

Tuesday 8:00 AM
March 21, 2023
Room: 25A
Location: SDCC

Session Chair: Wei-Ying Chen, Argonne National Laboratory


8:00 AM  Invited
Utilizing High-energy X-rays for Microstructural Characterization of Metallic Hydrides: Reeju Pokharel1; Samantha Lawrence1; Travis Carver1; Sangwon Lee1; Donald Brown1; 1Los Alamos National Laboratory
    The crystallographic location of hydride formation and its effects on structure property changes in metallic materials is poorly understood. Here, we have utilized high-energy synchrotron X-rays to non-destructively probe bulk metallic samples to characterize metallic hydrides formation with respect to crystallographic grains and studied how the presence of hydrides give rise to micro-mechanical stress fields development. High-energy X-ray diffraction microscopy (HEDM) in conjunction with micro-tomography provided a unique way for bulk microstructural characterization, affording spatially resolved crystallographic orientation, volumetric density maps, and grain resolved micromechanical fields measurements in three-dimension. We have demonstrated their capability to high-Z materials to understand the effect of hydrogen exposure in microstructure development. Specimens are prepared under various conditions, to observe early-stage nucleation and growth process of metallic hydrides. The non-destructive nature of these characterization techniques provides unprecedented experimental data for development and validation of theoretical codes for material performance prediction under extreme operating conditions.

8:30 AM  
Deep Learning Defect Detection in Electron Microscopy of Radiation Damage in Metals: Dane Morgan1; Ryan Jacobs1; Mingren Shen1; Priyam Patki2; Matthew Lynch2; Kevin Field2; 1University of Wisconsin-Madison; 2University of Michigan, Ann Arbor
    In this talk we discuss our recent work on automating detection of defects in electron microscopy images of irradiated metals. We demonstrate the capabilities of deep learning machine learning approaches to find the location and geometry of different defects in irradiated alloys, such as dislocation loops, black dot interstitial clusters, and cavities. We show that performance comparable to human analysis can be achieved with relatively small training data sets consisting of order one thousand labeled defects. We explore multiple avenues of assessment and our results suggest that averaging over many images can reduce the impact of errors. We explore convergence of the results with number of training samples, finding that certain defect types are significantly less well detected, likely due both to their having reduced sampling and greater variability.

8:50 AM  
Uncovering Transient Grain Boundary Absorption States Using Deep Learning Object Detection: Emily Hopkins1; Sicong He2; Ryan Jacobs3; Priyam Patki4; Chang-Yu Hung1; James Nathaniel5; Dane Morgan3; Kevin Field4; Jaime Marian2; Mitra Taheri1; 1Johns Hopkins University; 2University of California - Los Angeles; 3University of Wisconsin - Madison; 4University of Michigan; 5Sandia National Laboratories, CA
    Achieving radiation tolerance in crystalline materials will require a thorough understanding of defect evolution and corresponding material responses to ion bombardment. Tailoring grain boundaries to behave as enhanced defect sinks poses a potential solution toward the development of more radiation tolerant materials; however, critical nuances illustrating the microstructural response of grain boundaries under irradiation have yet to be explained. In particular, the relationship between GB structural states and their effect on the rate of defect absorption is unclear. In this study, we utilize automated object detection models of in situ TEM experiments to offer new insight into transient GB states and analyze cyclic recovery using rate theory models. By providing an indicator of changes in GB absorption mechanisms, we move closer to explaining GB metastability with the onset of radiation damage.

9:10 AM  Invited
Advanced In Situ Mechanical Testing Approaches to Evaluate the Degradation of Nuclear System Components: Maxim Gussev1; David McClintock1; Kevin Field2; Ercan Cakmac1; Travis Dixon1; 1ORNL; 2University of Michigan
     In the recent two decades, common mechanical testing techniques showed significant progress, being coupled with advanced tools like EBSD. The present work combines own authors’ results and a limited literature review to discuss the advantages, challenges, and limitations of several advanced experimental approaches for testing irradiated specimens. In-house manufacturing of irradiated specimens is described in detail. Among the discussed experimental techniques of special focus are: (1) SEM/EBSD, allowing for investigating strain-induced phenomena, like lattice rotation, twinning, phase instability, and cracking; (2) Digital image correlation (DIC) with focus on in-SEM applications (µDIC). Examples are given, including a technique based on imaging radiation-induced voids via BSE contrast; (3) High-resolution EBSD (HR-EBSD). The approach relies on an in-depth analysis of diffraction patterns to retrieve in-grain stresses and local dislocation densities; (4) In-situ X-ray tomography, allowing for detecting and tracking pores, cracks, and discontinuities in the specimen volume.

9:40 AM Break

10:00 AM  
Precipitate and Cavity Evolution in Alloy 718 Under High Temperature In-situ Ion Irradiation using Machine Learning: Stephen Taller1; Timothy Lach1; Kai Sun2; 1Oak Ridge National Laboratory; 2University of Michigan
    Ni-based superalloys are a candidate alloy class for advanced reactor applications because of their intrinsic creep resistance, corrosion resistance and high strength. Two Inconel 718 heats, one conventional and one additively manufactured, with high pre-existing precipitate densities were evaluated using in-situ dual ion irradiations up to 10 dpa using 1.17 MeV Kr ions with 400 appm He/dpa co-injected at 500-700°C at the Michigan Ion Beam Laboratory. HAADF images were collected continuously, and a dynamic segmentation convolutional neural network classified features in each image with several computer vision algorithms to track feature properties across frames. Pre-existing precipitates dissolved early (< 1 dpa) for all conditions. At 500°C, small cavities nucleated by 1 dpa, and phases with similar contrast to γ″ and δ emerged near 5 dpa. At 600°C and 700°C, both cavity nucleation and precipitate evolution were accelerated. The results are discussed in the context of rate theory modelling.

10:20 AM  
Particle-induced X-ray Emission Spectroscopy (PIXE) for In Situ Monitoring of Corrosion Under Proton Irradiation in the Irradiation-corrosion Experiment (ICE): Franziska Schmidt1; Matthew Chancey2; Hyosim Kim2; Yongqiang Wang2; Peter Hosemann1; 1University of California Berkeley; 2Los Alamos National Laboratory
    Understanding the response of materials to simultaneous irradiation and corrosion is vital for the development of structural alloys for the next generation of nuclear reactors and their coolants. Irradiation-corrosion experiments with new coolants, such as heavy liquid metals and molten salts, are difficult to conduct and often only yield data during post-experimental analysis. This means that multiple experiments are needed to obtain information about the kinetics of the corrosion process under irradiation, and that each data point has experiment-specific uncertainties connected to it. Particle-induced x-ray emission spectroscopy (PIXE) is supposed to fill this gap using continuous measurements of x-ray intensities from the sample and the corrosive medium during irradiation. We will present a quantitative interpretation of Fe sample thickness changes due to simultaneous LBE corrosion and 4 MeV-proton irradiation. Additionally, we will also discuss early attempts to obtain similar PIXE data with molten salt as the corrosive medium.