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MSE Seminar: “What Governs Grain Boundary Migration?”
October 20, 2022 at 10:30 PM - 11:30 PM
Curvature is the common driving force for grain boundary motion in all polycrystals. However, models and simulations derived from curvature-based motion cannot predict irregular, albeit commonly observed, grain growth behavior. To build better predictive models, we need to employ new tools to understand what governs grain growth. First, I will demonstrate how high energy x-ray diffraction microscopy (HEDM) can be used to observe grain growth in real 3D polycrystalline systems. In a grain growth study employing HEDM of strontium titanate, we find that curvature is a poor predictor of grain boundary migration. Instead, anisotropic grain boundary properties are hypothesized to override the contribution of curvature. Second, I will describe how reinforcement learning, a machine learning tool, can capture the underlying behavior of an evolving Markov decision process and “teach” it to maximize the “rewards” regarding the agreement between prediction and simulation. To demonstrate the feasibility of this approach, we built a deep reinforcement model that emulates grain growth by training on Monte Carlo Potts grain growth simulations. The developed reinforcement model was validated on different microstructural architectures to ensure that it captures the underlying physics. The accuracy of our short and long-term predictions will be evaluated. Then, I will discuss how HEDM and our machine learning model can be combined to understand how anisotropic grain boundaries migrate in 3D polycrystals.
Amanda R. Krause
Assistant Professor, Materials Science and Engineering Department, Carnegie Mellon University
Amanda R. Krause is an Assistant Professor in the Materials Science and Engineering Department at Carnegie Mellon University. She received her B.S. and M.S. in Materials Science and Engineering from Virginia Tech, and her Ph.D. in Materials Science from Brown University. Before joining Carnegie Mellon University in 2022, she was an Assistant Professor at University of Florida (2019-2022) and a post-doctoral research associate at Lehigh University. Her research focus is engineering grain boundaries and microstructures for improving the mechanical performance and degradation response of ceramics used in extreme environments. She is a recipient of the NSF CAREER award (2022).