Grain Boundaries and Interfaces: Metastability, Disorder, and Non-Equilibrium Behavior: Behaviors at Extreme Environments
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Computational Materials Science and Engineering Committee, TMS: Chemistry and Physics of Materials Committee, TMS: Phase Transformations Committee
Program Organizers: Yue Fan, University of Michigan; Liang Qi, University of Michigan; Jeremy Mason, University of California, Davis; Garritt Tucker, Colorado School of Mines; Pascal Bellon, University of Illinois at Urbana-Champaign; Mitra Taheri, Johns Hopkins University; Eric Homer, Brigham Young University; Xiaofeng Qian, Texas A&M University

Monday 2:00 PM
February 28, 2022
Room: 304C
Location: Anaheim Convention Center

Session Chair: Yue Fan, University of Michigan, Ann Arbor; Pascal Bellon, UIUC

2:00 PM  Invited
Radiation Effects on Interfacial Phenomena in Ceramics: Izabela Szlufarska1; Hongliang Zhang1; Jianqi Xi1; Brian Sheldon2; Christos Athanasiou2; Xing Wang3; 1University of Wisconsin-Madison; 2Brown University; 3Penn State University
    Interfaces are known to play an important role in controlling a plethora of properties relevant for structural materials, including mechanical strength, toughness, and corrosion resistance. However, the atomic and the chemical structures of interfaces are not static when the material is driven out of equilibrium by exposing it to high temperature, stress, or irradiation. In this talk I will discuss the effects of radiation on interfaces in SiC-based materials. I will demonstrate that radiation-induced segregation (RIS) of constituent elements is possible in ceramics, even when they form line compounds, and I will discuss the impact of RIS on corrosion resistance. Finally, I will demonstrate that ion implantation can be used as a tool for nano-engineering of interfaces in SiC-carbon nanotube composites, leading to significant improvements of fracture toughness.

2:30 PM  Cancelled
Interpreting Discrete GND Footprints of Atomic-level Irradiation Defects Near Grain Boundaries: Jaime Marian1; Mitra Taheri2; David Srolovitz3; 1University of California, Los Angeles; 2Johns-Hopkins University; 3City University of Hong Kong
    Irradiation damage is highly dependent on a material's microstructure. Grain boundaries (GB) are known to couple strongly to irradiation defects, by acting as sinks and sources of point defects and defect clusters, thus influencing microstructual evolution during irradiation. Defect interactions with grain boundaries may induce a series of transformations that are challenging to interpret experimentally. Nye tensor analysis based on mapping lattice curvature to geometrically-necessary dislocation (GND) signals can be used to correlate defect absorption and lattice transformations near GB. However, such correlations are highly nuanced due to the atomistic complexity and variability of defect clusters and GB structures. In this presentation, we provide a rigorous computational mapping between the GND tensor analysis and atomic-level descriptions of irradiation loops, highlighting the pros and cons of using such technique for interpretation of experimental observations.

3:00 PM  
Phase Field Modeling of the Coupling between Compositional Patterning and Radiation Induced Precipitation at Grain Boundaries and Dislocation Loops in Immiscible Binary Alloys during Irradiation: Gabriel Franck Bouobda Moladje1; Robert S Averback1; Pascal Bellon1; 1University of Illinois at Urbana-Champaign
    Modeling and experiments have established that the chemical mixing forced by irradiation can induce self-organization in immiscible alloys, with steady-state compositional patterns comprised of intragranular nanoprecipitates. This self-organization, however, can be destabilized by the loss of solute to sinks such as grain boundaries (GBs) and dislocation loops owing to solute drag by point defects. A new phase field model is introduced to investigate the competition between these phenomena under irradiation. Low angle GBs are modeled as dislocation arrays. Point defects migration, which is biased by the sink strain fields, can lead to solute drag depending upon the sign and amplitude of solute-point defect interactions. Using parameters for dilute Al alloys, e.g., Al-Sb, it is found that irradiation-induced patterning at GBs and loops can co-exist with intraganular patterning. This global patterning may be beneficial for radiation tolerance. The results are compared to recent experiments on these alloys.

3:20 PM  
Plastic Deformation in Nickel Bicrystals Containing Helium Bubbles: Tung Yan Liu1; Michael Demkowicz1; 1Texas A&M University
    We present molecular dynamics simulations of plastic deformation of nickel (Ni) bicrystals containing nano-scale helium bubbles. The models are based on experimental characterization of defect structures in Ni-base alloy components irradiated during service in pressurized heavy water reactors. We examine dislocation nucleation and motion, slip band formation, deformation-induced changes in bubble shape, as well as slip interactions with grain boundaries. We also assess how these behaviors are affected by the introduction of a rigid inclusion at a grain boundary. The implications of our work for understanding the lifetime and performance of Ni-base components in nuclear fission applications are discussed.

3:40 PM Break

3:55 PM  Invited
Computational Insights into the Interactions of Defects with Grain Boundaries: Blas Uberuaga1; 1Los Alamos National Laboratory
    How defects interact with grain boundaries has been a long-studied question, particularly in the context of radiation damage. We know, for example, that grain boundaries can act as fast pathways for transport. However, there is still much that is unknown. In this talk, we will describe the results of computational simulations that target novel aspects of this problem. First, we examine how defect clustering within the grain boundary plane, which one might expect to occur during irradiation but potentially also thermally, impacts defect mobility. Second, we consider how alloying – changing the local chemistry by introducing a solute – of the boundary affects interstitial and vacancy-mediated migration. Finally, we construct a model of defect saturation at boundaries during irradiation in ionic materials, finding that the accumulated charge significantly impacts defect evolution. These results provide new insight into the synergy between grain boundaries and defect evolution in non-equilibrium environments.

4:25 PM  
Integration of Microscopy and Deep Learning to Define Localized Grain Boundary Sink Efficiency: Emily Hopkins1; Emma Liu1; Ryan Jacobs2; Priyam Patki3; James Nathaniel1; Kevin Field3; Dane Morgan2; Mitra Taheri1; 1Johns Hopkins University; 2University of Wisconsin - Madison; 3University of Michigan
    Achieving radiation tolerance in crystalline materials will require a thorough understanding of defect evolution and corresponding grain boundary sink efficiency. Defect denuded zones have been widely accepted as descriptors of grain boundary sinks. However, recent studies have shown that denuded zone measurement may omit critical nuances illustrating the behavioral response of grain boundaries given regions of varying absorption rates and localized strain complexes. In this study, we explore the automated use of the object detection model YOLO to probe sink efficiency in regions of fluctuating grain boundary strain. Used in combination with in situ transmission electron microscopy, we can work toward a deeper understanding of point defect absorption and grain boundary sink behavior through the quantitative visualization of temporal defect evolution under irradiation.

4:45 PM  
Dynamic Interaction between Grain Boundary and Structural Defects by Molecular Dynamics Simulation: Liang Zhang1; Cheng Lu2; Yasushi Shibuta3; 1Chongqing University; 2University of Wollongong; 3The University of Tokyo
    Understanding the interaction between grain boundary (GB) and various structural defects is of great significance to design high-performance metallic materials through GB engineering. We carried out molecular dynamics (MD) simulations to investigate the dynamic interaction between GBs and different types of structural defects in copper, including void, stacking fault tetrahedra (SFT), dislocation loop, and hydrogen bubble. (1) The GB can migrate itself under the shear strain and can serve as a sink to remove the structural defects. The sink efficiency of GBs is sensitive to their structural characteristics, the size of the defects, and temperature. (2) The dynamic migration of high-angle GBs can significantly accelerate the dissolution time of the structural defects, and GB structural phase transformation provided an efficient diffusion channel for transporting the point defects. (3) Two possible self-healing mechanisms of nanotwinned metals under irradiation were proposed by considering the defective coherent twin boundary structures.