Probing Defect Properties and Behavior under Mechanical Deformation and Extreme Conditions: Radiation Response and Defect Evolution
Sponsored by: TMS Nanomechanical Materials Behavior Committee, TMS Nuclear Materials Committee, TMS Mechanical Bahavior of Materials Committee
Program Organizers: Zhe Fan, Lamar University; Tianyi Chen, Oregon State University; Shijun Zhao, City University of Hong Kong; Mitra Taheri, Johns Hopkins University; Yury Osetskiy, Oak Ridge National Laboratory
Wednesday 8:00 AM
October 20, 2021
Room: B140/141
Location: Greater Columbus Convention Center
Session Chair: Xing Wang, Pennsylvania State University; Tianyi Chen, Oregon State University
8:00 AM Invited
Radiation Enhanced Diffusion in Fe2O3 and Cr2O3: Kayla Yano1; Aaron Kohnert2; Amitava Banerjee2; Danny Edwards1; Edward Holby2; Tiffany Kaspar1; Hyosim Kim2; Sandra Taylor1; Yongqiang Wang2; Blas Uberuaga2; Daniel Schreiber1; 1Pacific Northwest National Laboratory; 2Los Alamos National Laboratory
Within a nuclear reactor, many materials encounter multiple extreme environments, such as irradiation and corrosion. To understand the potential synergies between these two environments, it is critical to determine fundamental modes of radiation enhanced diffusion (RED). Here, using both modeling and experiment, we examine the mechanisms of radiation-enhanced diffusion in two oxides representative of the scales formed on corroded iron and steel. Oxide films with isotopic tracer layers are deposited and irradiated with ion beams and then characterized via atom probe tomography to determine the extent of RED in these scales. These results are then compared to an atomistically-informed mesoscale model of transport to identify the mechanisms responsible for RED. Together, these results provide new insight into the mechanisms driving RED in these oxides and the potential impact of radiation damage on corrosion.
8:30 AM
Impact of Grain Boundary and Surface Diffusion on Fission Gas Release in UO2 Nuclear Fuel Using a Phase Field Model: Md Ali Muntaha1; Dong-Uk Kim1; Michael Tonks1; 1University of Florida
This study aims to quantify the importance of grain boundary and surface diffusion on the fission gas release mechanism in UO2 nuclear fuel. Most computational studies of fission gas bubble behavior found in the available literature do not consider faster diffusion along grain boundaries, triple junctions, and gas bubble surfaces. Our study has investigated the importance of grain boundary and surface diffusion on fission gas release in UO2 nuclear fuel. To do that, we have added a free surface on a specific boundary on the domain to observe the gas release amount through the free surface. We have incorporated diffusion heterogeneity for providing a faster diffusion path along the grain boundary and interface. We have developed and applied a phase-field model using an open-source finite element tool MOOSE for mesoscale modeling. Our model predicts that incorporating diffusion heterogeneity changes the way microstructure evolves and changes the fission gas release rate.
8:50 AM Invited
Long-range One-dimensional Glide of Defect Clusters in Irradiated Materials: Experimental Evidence and Consequences: Steven Zinkle1; Ling Wang2; Yan-Ru Lin1; 1University of Tennessee; 2Oak Ridge National Lab
Multiple molecular dynamics simulations and limited in-situ TEM experimental studies have reported evidence for high mobility of vacancy or interstitial defect clusters, with preferential one-dimensional (1D) glide. However, the relative fraction of glissile clusters and their impact on overall defect microstructural evolution in irradiated materials is not well quantified. Experimental in-situ and ex-situ observations of radiation induced loss of precipitate coherency over a wide range of irradiation temperatures and precipitate sink strengths, along with observations of void and dislocation loop behavior in the vicinity of planar defect sinks (grain boundaries and surfaces) will be summarized. Analysis of these results indicates that 1D glide of interstitial clusters is particularly significant when the matrix sink strength is below ~1x1014/m2. At higher matrix sink strengths, effects associated with 1D glide rapidly become less noticeable. The practical impact of 1D defect cluster glide on understanding microstructural evolution of irradiated materials will be discussed.
9:20 AM Invited
Now On-Demand Only - The Role of Anisotropy on the Defect Self-organization in Metals under Irradiation: Cheng Sun1; 1Idaho National Laboratory
Self-organization of defects has been widely observed in far-from-equilibrium systems and leads to the formation of ordered defect superlattice structures in materials. The formation of void or bubble superlattices has been reported in both metallic and ionic systems under different irradiation conditions, including neutron, ion, and electron irradiation. In nuclear reactor environments, the self-organization of fission products in nuclear fuels mitigates the fission-gas -release and swelling. Fundamental understanding of the underlying physics that govern the defect self-organization is essential for the prediction of lifetime of materials in nuclear reactors. In this report, we summarize our recent research on the self-organization of noble gas bubbles, solid nano-clusters, and voids in fcc and bcc metals and their stability under irradiation. The role of elastic and diffusional anisotropy on defect self-organization will be discussed.
9:50 AM Invited
Surprisingly High Irradiation-induced Defect Mobility in Fe3O4 as Revealed through In Situ Transmission Electron Microscopy: Djamel Kaoumi1; Martin Owusu-Mensah1; Angelica Lopez Morales1; Kayla Yano2; Tiffany Kaspar2; Daniel Schreiber2; Blas Uberuaga3; 1North Carolina State University; 2Pacific Northwest National Laboratory; 3Los Alamos National Laboratory
While radiation-enhanced diffusion is a well know phenomenon, ceramics have often been considered to be more resilient to radiation, with some simulation studies suggesting an inherent difficulty to form stable dislocation loops. However recent ion irradiations of Metal/Oxide (e.g. Fe/Fe3O4) heterostructures done in-situ in a TEM showed enhanced mobility of defects in the ceramic part more so than the metal part. Indeed, it was shown that much higher defect mobility induced in the ceramic led to quicker defect loss to sinks and lower density of visible loops in the oxide compared with the metal Fe. The question of radiation-enhanced diffusivity of defects in ceramics is not as “straightforward” as in metals due to the nature of the defects being charged. We provide a thorough discussion of the current models including ionization induced diffusion (IID) and electro-migration and how our experiments question or support them.
10:20 AM Break
10:40 AM Invited
Multimodal and Multiscale Defect Characterization and Property Correlation for Nuclear Fuel and Materials via Advanced Post Irradiation Examination Techniques: Peng Xu1; 1Idaho National Laboratory
Nuclear fuel and materials are used in services under extreme environments such as high radiation field, high temperature, corrosion, and pressure conditions. Significant advancement was made in recently years to detect and observe the defects in radioactive materials and to understand its properties and behaviors via advanced characterization tools, such as high resolution 4D transmission electron microscopy (4D-TEM), atom probe tomography (APT), x-ray and neutron imaging and radiography, spacial domain thermoreflectance (SDTR), nanoscale and microscale testing, and real time in-situ tests. In this talk I will discuss defects characterization and evaluation and their impact on mechanical properties and thermal properties for novel fuel and nuclear materials for the light water reactors and the next generation advance reactors at the Post Irradiation Examination facilities at Idaho National Laboratory. The materials of interest include UN and composite fuels, TRISO fuels, metallic fuels, SiC Composites, advanced manufactured and coating materials.
11:10 AM
Measuring Elemental Segregation and Vacancy Migration Using Atom Probe Tomography: Xing Wang1; Jonathan Poplawsky2; Yanwen Zhang3; Karren More2; 1Pennsylvania State University; 2Oak Ridge National Laboratory; 3University of Tennessee
Cavity is an important defect structure in irradiated materials. Cavity growth is often controlled by the clustering of vacancies. Due to different element diffusivities mediated by vacancies, the vacancy flux to cavities will lead to local elemental segregations, providing a unique probe to quantify vacancy migration and its effects on cavity growth. Here, atom probe tomography (APT) was used to accurately measure segregations near nanoscale cavities in concentrated solid solution alloys (CSAs). We show that Cr is depleted more than other elements, indicating faster vacancy migration via this element and explaining the larger cavity growth rate in CSAs containing Cr. Segregation analyses also find Pd repels other oversized elements such as Fe and Cr, adding extra migration paths for vacancies and suppressing cavity growth. This work was supported by EDDE, an EFRC funded by U.S. DOE-BES. APT was conducted at ORNL’s CNMS, a U.S. DOE Office of Science User Facility.