Advanced Characterization of Materials for Nuclear, Radiation, and Extreme Environments III: Thermomechanical Properties
Sponsored by: TMS Nanomechanical Materials Behavior Committee, TMS Nuclear Materials Committee
Program Organizers: Cody Dennett, Commonwealth Fusion Systems; Samuel Briggs, Oregon State University; Christopher Barr, Naval Nuclear Laboratory; Michael Short, Massachusetts Institute of Technology; Janelle Wharry, Purdue University; Cheng Sun, Clemson University; Caitlin Kohnert, Los Alamos National Laboratory; Khalid Hattar, University of Tennessee Knoxville; Yuanyuan Zhu, University Of Connecticut
Monday 8:00 AM
October 10, 2022
Room: 329
Location: David L. Lawrence Convention Center
Session Chair: Michael Short, Massachusetts Institute of Technology; Cody Dennett, Commonwealth Fusion Systems
8:00 AM Invited
Defect Structure and Property Evolution in Ion-irradiated Tungsten: Progress towards a Comprehensive Understanding: Felix Hofmann1; Daniel Mason2; Abdallah Reza1; Suchandrima Das1; Hongbing Yu3; Sergei Dudarev2; 1University of Oxford; 2UKAEA; 3Canadian Nuclear Laboratories
Tungsten is a promising candidate for future fusion reactor armor components. It is also an attractive model system to gain fundamental insight into the link between irradiation-induced defects and the changes in mechanical and physical properties they bring about. We consider self-ion-implanted tungsten exposed to damage levels from 0.0001 dpa (low dose limit) to 10 dpa (high dose limit). We have characterized the evolution of lattice strain (using X-ray micro-diffraction and electron diffraction), elastic properties (using surface acoustic waves), plastic deformation behavior (using nano-indentation) and thermal transport properties (using transient grating spectroscopy) as a function of damage dose. Using an array of different simulation tools (density functional theory calculations, molecular dynamics simulations, crystal plasticity modelling, kinetic theory thermal transport calculations) the measured changes can be quantitatively linked to the underlying irradiation-induced defects. Combining all this information, a coherent picture of how irradiation changes tungsten begins to emerge.
8:30 AM
Characterization of Simultaneous High-energy Proton and Spallation-Neutron Radiation Effects in Structural Alloys: Timothy Lach1; Maxim Gussev1; David McClintock1; 1Oak Ridge National Laboratory
Simultaneous high-energy proton and spallation-neutron irradiation induce microstructural and mechanical responses in structural materials that are unique from irradiation only by fission neutrons or ion-beams. In addition to recoil damage at moderate temperatures (100-200 °C), transmutation reactions produce large levels of retained helium and hydrogen. The target and proton beam window (PBW) at the Spallation Neutron Source at Oak Ridge National Laboratory are irradiated in these unique environments during operation. Neutron production is dependent on the proper operation of the target and PBW; therefore, accurate understanding of the radiation-induced changes to the microstructure and mechanical properties are essential for ensuring reliable operation. Samples from 316L stainless steel targets and an alloy 718 PBW were analyzed using several complementary advanced characterization techniques, including tensile testing with digital image correlation, analytical in-situ/ex-situ electron microscopy, and thermal desorption spectrometry. Intriguing behaviors like radiation-induced ductility, strain localization, and bubble/void formation will be discussed.
8:50 AM
Deformation Twinning versus Slip in Ni-based Alloys, Containing Pt2Mo-structured, Ni2Cr-typed Precipitates: Hi Vo1; Khanh Dang1; Fei Teng2; Matt Schneider1; Benjamin Eftink1; Stuart Maloy3; Laurent Capolungo1; Peter Hosemann4; 1Los Alamos National Laboratory; 2Idaho National Laboratory ; 3Pacific Northwest National Laboratory; 4UC Berkeley
Nickel-based alloys are extensively used in a wide range of extreme environments because of their exceptional mechanical properties. The excellent strength of these alloys is derived from the addition of long-range ordered precipitates, introduced by thermal aging. The interactions between the dislocations and LRO precipitates dictate the deformation modes and plastic response in these alloys. While the majority of studies have focused on L12-structured precipitate-strengthened Ni-based alloys, less work has considered the Ni-based alloys containing Pt2Mo-structured, Ni2(Cr,Mo)-typed precipitates. In these alloys, Pt2Mo-structured precipitates enable room-temperature deformation twinning in addition to slip, which increases strain hardenability measured from bulk mechanical testing. In this work, molecular dynamics examined the possible types of dislocation and Pt2Mo-structured precipitate interactions at low temperature. Combined with in situ micromechanical testing, the role of resolved shear stresses on dislocation partials were shown to directly influence the activation of slip versus twinning.
9:10 AM
Automated In Situ Deformation Characterization via Analytical SEM during High Temperature Tensile Testing: Sebastian Krauss1; Hrishi Bale1; Stephen Kelly1; 1ZEISS Research Microscopy Solutions
Tensile testing is the backbone of mechanical characterization. The possibility to combine mechanical testing with advanced imaging and characterization methods at high temperatures up-to 800°C opens new possibilities for materials research in the nuclear and space applications. In this work in-situ annealing experiments are shown, where the grain growth is observed via EBSD and EDS. Different annealing states are achieved for a variety of model alloy samples. Using EBSD information, high Schmid factor grains were identified and monitored during the in-situ tensile experiment enabling the image acquisition from the early onset of yielding in the first few grains. Furthermore, in-situ tensile tests on steel samples at a temperature of 800 °C clearly reveal slip band formation using BSD contrast. Results demonstrate the automated workflow of in-situ SEM imaging incorporating feature tracking to enable precise region of interest imaging. Additionally combining digital image correlation approach to map strains during deformation.
9:30 AM
Applications of Cryogenic Nanomechanical Testing: Eric Hintsala1; Douglas Stauffer2; 1Bruker Nano Surfaces and Metrology; 2Bruker Nano Surfaces & Metrology
The combination of nanomechanical testing and cryogenic temperature-capability enables the exploration of a rich variety of materials’ behaviors, from ductile-to-brittle transitions in metals to glass transitions in polymers. Moreover, the highly localized measurements can target individual regions of the microstructure to evaluate their response and separate the response of thin films from their substrates. These capabilities can be used to study applied problems, like reliability of components for winter and aerospace applications, and theoretical ones by exploring deformation mechanisms across the time and temperature space. Two case studies will be presented, the determination of the glass transition temperature in polymer thin films utilizing dynamic indentation methods, and the phase-specific ductile-to-brittle transition characteristics of a plain steel.
9:50 AM Break
10:10 AM Invited
Advanced In-situ and Post-Irradiation-Examination Thermal Conductivity Measurements of Nuclear Fuels and Materials: Zilong Hua1; Amey Khanolkar1; Cody Dennett2; Robert Schley1; Austin Fleming1; Colby Jensen1; Marat Khafizov3; David Hurley1; 1Idaho National Laboratory; 2Commonwealth Fusion Systems; 3Ohio State University
Thermal conductivity of nuclear fuels is directly related to reactor safety and efficiency. In this talk, unique advanced capabilities residing at Idaho National Laboratory (INL) that can characterize thermal conductivity and diffusivity of nuclear fuels and materials on microscopic and mesoscopic length scales are presented with the latest experimental results. Using laser-based approaches such as thermoreflectance and photothermal radiometry, thermal transport measurements can be performed as a part of Post-Irradiation Examination (PIE) or in situ. It provides novel insights of fundamental mechanisms of microscale heat conduction involving microstructural defect generation and evolution of nuclear fuels, which will benefit advanced fuel performance codes and aid in the development of high thermal conductivity fuels.
10:40 AM
In-situ Thermal Diffusivity Recovery and Defect Annealing Kinetics in Self-ion Implanted Tungsten Using Transient Grating Spectroscopy: Mohamed Abdallah Reza1; Hongbing Yu2; Cody Dennett3; Kenichiro Mizohata4; Felix Hofmann1; Guanze He1; 1University of Oxford; 2Canadian Nuclear Laboratories; 3Massachusetts Institute of Technology; 4University of Helsinki
Irradiation damage alters the properties of tungsten, the main candidate material for fusion reactor armor. Using transient grating spectroscopy with in-situ annealing, we study the recovery of thermal diffusivity in self-ion implanted tungsten up to 800C for doses from 0.00032 to 3.2 displacements per atom (dpa). Room temperature thermal diffusivity recovers from ~45% to 75% of the pristine value for the highest damage level. Using a kinetic theory model we interpret this recovery in terms of annealing of irradiation-induced defects. Our results show a large removal of defects at ~350C, consistent with the temperatures for mono-vacancy mobility in tungsten. This suggests that the small point defects, invisible to TEM, are the main contributors to thermal diffusivity degradation in room-temperature-irradiated tungsten. The defect recovery estimates also agreed well with TEM annealing experiments. These new results suggest that annealing at relatively modest temperatures may be used to reduce irradiation-induced thermal diffusivity degradation.
11:00 AM
Detection of Radiation Vulnerability in Microelectronic Systems: Sergei Stepanoff1; Md Rasel2; Aman Haque2; Douglas Wolfe1; Fan Ren3; Stephen Pearton3; 1The Applied Research Laboratory; 2The Pennsylvania State University; 3University of Florida
As electronic systems become larger and more complex, detection of the most vulnerable regions (MVR) to radiation exposure becomes increasingly difficult and time consuming using traditionally accepted methods, such as pulsed laser, microbeam, or in-situ radiation techniques, for MVR detection. We present a heuristic approach that topologically maps two device conditions to identify the MVR. The first identifies regions with the highest mechanical strain or density of defects and interfaces using lock-in thermography to construct a phase map of the device structure. The second identifies regions with the highest electrical field. It is hypothesized that the region with the highest structural phase contrast and electrical field will also exhibit the highest sensitivity to incoming radiation. The design is used to examine the well-studied operational amplifier LM124, which shows very good agreement with the literature and has potential to improve analysis time by orders of magnitude over current testing methodologies.
11:20 AM
Ring Pull Testing: The Effect of Mandrel Diameter: Mathew Hayne1; Peter Beck1; James Valdez1; Cheng Liu1; Thomas Nizolek1; Tarik Saleh1; Stuart Maloy1; Benjamin Eftink1; 1Los Alamos National Laboratory
Gaugeless ringpull testing is a convenient test to evaluate the cladding in the hoop direction, due to the fact the samples are easy to machine remotely for activated materials, however, the results are complicated to interpret. The impact of differences in fixture design are important and not well understood, making comparisons between tests performed by different groups difficult. To better understand the impact of mandrel sizes, a range of mandrel diameters were used to test accident tolerant C26M FeCrAl alloy. Global stress and strain measurements were investigated as well as local digital image correlation strain measurements. The measured 0.2% offset stress as well as the ultimate stress, showed no statistically significant differences with respect to mandrel diameter. The elongation measurement, on the other hand, was shown to be highly dependent on mandrel diameter. This talk will go through considerations for mandrel size choice based on tube geometry.