Elastic measurements of plasma spray refractory metal coatings using thermal cycling of bi-layered beams .
Abstract not provided.
Vackel, Andrew↗
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Contribution of cryogenic thermal cycling to the atomic dynamics in a La-based bulk metallic glass with different initial states
Structural rejuvenation in metallic glasses (MGs) induced by cryogenic thermal cycling has been intensively studied. However, the effect of thermal cycling on the atomic dynamics in MGs is still missing. In this work, we present a systematic study on the atomic dynamics in a La-based MG affected by sub-Tg annealing and thermal cycling. We find that the thermal cycling has little effect on the atomic dynamics in both as-cast and annealed MGs although it could significantly increase the free volume and change mechanical properties of the as-cast MG sample. In contrast, both the structure and mechanical properties of the well-relaxed sample are almost unchanged by thermal cycling. Further, the increased open volume, mainly in the form of atomic vacancies, does not greatly promote the atomic dynamics in the as-cast MG sample, indicating that the free volume induced by thermal cycling is not the key factor in stimulating the β-relaxation and the boson peak in the studied MG.
36 MATERIALS SCIENCE↗
Mechanistic transition of stainless steel 304L corrosion in MgCl 2 phase change material under thermal cycling
Magnesium chloride (MgCl 2 )-based molten salt phase change materials (PCMs) are promising candidates for thermal energy storage (TES) owing to their advantageous thermophysical properties, however, their high corrosivity in the molten state limits material compatibility. In this study, the corrosion behavior of 304?L stainless steel (SS304L) exposed to MgCl2 PCM was investigated as a function of thermal cycling (up to 9000 cycles) relevant to PCM-based TES systems. Microstructural changes and elemental redistribution at the alloy-salt interface under thermal cycling conditions were characterized using synchrotron-based X-ray fluorescence (XRF) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS). Results show that corrosion is governed by selective Cr-dissolution and elemental diffusion near the interface and grain boundaries. A clear transition in the dominant corrosion mechanism is observed with increasing thermal cycles. Surface corrosion is the dominant mechanism up to 1000 cycles, whereas intergranular corrosion becomes the primary degradation mode beyond 2000 cycles. These mechanistic changes are interpreted in terms of evolving interfacial chemistry, microstructure and the diffusion-driven redistribution of alloying elements.
36 MATERIALS SCIENCE↗
Activation Energy for End-of-Life Solder Bond Degradation: Thermal Cycling of Field-Aged PV Modules
The longevity of solar photovoltaic modules depends on the durability and reliability of their components, one of which is the solder bonds in interconnect ribbons. The solder joints experience stresses from thermal cycling and constant elevated temperatures (40 °C-70 °C) in regular field operation leading to thermo-mechanical fatigue and intermetallic compound formation. To study the end-of-life wear-out mechanisms and to obtain activation energy of solder bond degradation, here two field-aged modules from Arizona-a 21-year-old Solarex MSX60 module (with Sn62Pb36Ag2 at the solder joints) and an 18-year-old Siemens M55 module (with Sn60Pb40 at the solder joints)-underwent 800 and 400 modified thermal cycles, respectively. Using three heating blankets, each module had three temperature zones maintained at 85, 95, and 105 °C during the 15-min hot dwell time of the thermal cycle. Cell-level series resistance data obtained from three temperature zones enabled the calculation of activation energy for solder bond degradation for the MSX60 and the M55 modules to be 0.12 eV and 0.35 eV, respectively. From each temperature zone in both modules, busbar-solder samples were obtained, imaged through SEM, and analyzed with energy-dispersive X-ray spectroscopy. In the MSX60 module with traces of Ag in the solder material, phase segregation and growth were primarily observed at high temperatures. For M55 modules without Ag in the solder material, major phase segregation was observed in all temperature zones. The IMC thickness for both modules increased with increasing module temperature. The beneficial effect of Ag in solder material on mitigating solder bond degradation is presented.
14 SOLAR ENERGY↗
An extreme thermal cycling reliability test of ATLAS ITk Strips barrel modules
At the end of Run 3 of the Large Hadron Collider (LHC), the accelerator complex will be upgraded to the High-Luminosity LHC (HL-LHC) in order to increase the total amount of data provided to its experiments. To cope with the increased rates of data, radiation, and pileup, the ATLAS detector will undergo a substantial upgrade, including a replacement of the Inner Detector with a future Inner Tracker, called the ITk. The ITk will be composed of pixel and strip sub-detectors, where the strips portion will be composed of 17,888 silicon strip detector modules. During the HL-LHC running period, the ITk will be cooled and warmed a number of times from about -35°C to room temperature as part of the operational cycle, including warm-ups during yearly shutdowns. To ensure ITk Strips modules are functional after these expected temperature changes, and to ensure modules are mechanically robust, each module must undergo ten thermal cycles and pass a set of electrical and mechanical criteria before it is placed on a local support structure. This paper describes the thermal cycling Quality Control (QC) procedure, and results from the barrel pre-production phase (about 5% of the production volume). Additionally, in order to assess the headroom of the nominal QC procedure of 10 cycles and to ensure modules don't begin failing soon after, four representative ITk Strips barrel modules were thermally cycled 100 times — this study is also described.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Investigation of Rapid, Moderate Temperature Change Thermal Cycles of a Micro-Tubular Flame-Assisted Fuel Cell
Despite many efforts and improvements over the last few decades, two of the major challenges facing solid oxide fuel cells (SOFCs) are slow heating rates to operating temperature (typically < 5 °C · min–1) and a limited ability to thermal cycle (<200 cycles). Recently, a novel hybrid setup that combines a fuel-rich combustion reformer with a SOFC was developed and utilized to investigate rapid heating, cooling, and thermal cycling of a micro-tubular SOFC. In this work, 3000 moderate thermal cycles are conducted at a heating rate exceeding 140 °C · min–1 and a cooling rate that exceeded 100 °C · min–1. The open-circuit voltage (OCV) was analyzed over the 150 h test, and a low degradation rate of ~0.0008 V per 100 cycles per fuel cell was observed in the absence of the current collector degradation. Unlike a previous test, which was conducted at lower temperatures, significant degradation of the current collector was observed during this test. Electrochemical impedance spectroscopy shows that degradation in the SOFC was due to increases in ohmic losses, activation losses at the cathode, and increased concentration losses.
Electrochemistry↗
Residual elastic strain evolution due to thermal cycling of a ceramic-metal composite (WC-Cu) via high energy X-ray diffraction and analytical modeling
Residual stress, when superimposed with in-service loading, can significantly reduce the lifetime and performance of a component. Ceramic-metal composites are susceptible to residual stresses due to the thermal expansion mismatch of the ceramic and metallic phases. The WC-Cu composite explored in the present study provides a promising combination of thermal conductivity and strength properties, while exhibiting counterintuitive improvements in strength and ductility after thermal cycling. Further, this work quantifies the evolution of the residual elastic strains as a result of processing and cyclic thermal loading in a co-continuous WC-Cu composite through experimental high energy X-ray diffraction and kinetics-based modeling. Both analyses indicate that processing-induced residual tensile stress in the copper phase is relieved upon subsequent thermal cycling, with kinetics modeling revealing the cyclic-dependent nature of the active power-law creep mechanisms. The results indicate that, through stress relaxation, this material system maintains structural stability during thermal cycling. The illustrated kinetics of relaxation can inform general material processors and designers of ceramic-metal composites to minimize detrimental residual stress and improve performance of these material systems.
36 MATERIALS SCIENCE↗
Microstructural stability of irradiated yttrium hydride under thermal cycles
Hydrides that retain their hydrogen in service are critical for advanced microreactor and space nuclear systems. Hydrogen retention is affected by evolving microstructure under temperature and irradiation extremes. This study investigated microstructural features in neutron-irradiated yttrium hydride and the stability of these features under thermal cycles. Differential scanning calorimetry was used to determine hydrogen desorption and temperatures at which significant phase changes are occurring, and transmission electron microscopy was used for microstructural analysis after each thermal cycle. Cyclic heating led to crystallization and epitaxial growth of surface oxidation and dehydriding of the matrix. Other features such as the bulk matrix crystal structure, irradiation-induced cavities, and matrix precipitation remained constant after thermal cycling. Results allow us to design better hydride alloys through microstructure tailoring and potential irradiation conditioning treatments.
36 MATERIALS SCIENCE↗
Quality concerns caused by quality control — deformation of silicon strip detector modules in thermal cycling tests
The ATLAS experiment at the Large Hadron Collider (LHC) is currently preparing to replace its present Inner Detector (ID) with the upgraded, all-silicon Inner Tracker (ITk) for its High-Luminosity upgrade (HL-LHC). The ITk will consist of a central pixel tracker and the outer strip tracker, consisting of about 19,000 strip detector modules. Each strip module is assembled from up to two sensors, and up to five flexes (depending on its geometry) in a series of gluing, wirebonding and quality control steps. During detector operation, modules will be cooled down to temperatures of about -35 °C (corresponding to the temperature of the support structures on which they will be mounted) after being initially assembled and stored at room temperature. In order to ensure compatibility with the detector's operating temperature range, modules are subjected to thermal cycling as part of their quality control process. Ten cycles between -35 °C and +40 °C are performed for each module, with full electrical characterisation tests at each high and low temperature point. As part of an investigation into the stress experienced by modules during cooling, it was observed that modules generally showed a change in module shape before and after thermal cycling. This paper presents a summary of the discovery and understanding of the observed changes, connecting them with excess module stress, as well as the resulting modifications to the module thermal cycling procedure.
47 OTHER INSTRUMENTATION↗
Microstructure Evolution of U–Zr System in A Thermal Cycling Neutron Diffraction Experiment: Extruded U–10Zr (wt. %)
Microstructure evolution of 1073 K extruded U–10Zr (wt. %) fuel during thermal cycling (303–1073 K with a ~9 hour hold at 873 K during cooling) was investigated using in situ neutron diffraction. Analysis was performed using Rietveld texture and crystal structure refinements from time–of–flight neutron diffraction data, with a focus on the evolution of textures and lattice parameters as a function of temperature. The α–U phase exhibits lattice contraction with increasing temperature along the b lattice direction and lattice expansion in the other directions while the other phases exhibit lattice expansion with temperature in all directions. Contrary to the established phase diagram, the β–U phase is absent at the temperatures of the thermal cycling. (001) α and (110) γ plane normals are observed with a strong preferred orientation along the extrusion direction. Finally, the variant selection of (001) α ||(110) γ is observed for the first time.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Report on Thermal Cycling Testing and Bimaterial Weld Development for a Passively Actuated Materials Surveillance Test Article
This report describes the continuation and conclusion of a thermal cycling test program designed to evaluate a family of passively actuated material surveillance test articles. Additionally, the report details a preliminary study of bimetallic welding between 316 stainless steel and TZM (tungsten-zirconium-molybdenum) alloy. The test program was ultimately successful in demonstrating the basic viability of the passively actuated test article concept as well as specifically validating the procedures developed to size specimens to mimic the mechanical response of operating components. The report discusses and summarizes the results of the complete test program which tested samples for more than 1,000 controlled thermal cycles. The weld development program included both stir friction and electron beam joining. The stir friction welding was ultimately successful, while the electron beam welding would require additional development. Ultimately, these test programs pave the way for implementing a materials surveillance program in future molten salt reactors (MSRs). The report conclusions outline a plan for transforming the research and developed described here into a definite set of practices and procedures for a surveillance program at a future operating reactor.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Phase evolution of U-Zr system in a thermal cycling neutron diffraction experiment: as-cast U-35Zr and U-50Zr
Here, phase evolution of as-cast U-35 wt% Zr and U-50 wt% Zr alloys during thermal cycling (303–1073 K) was investigated using in-situ neutron diffraction. Analysis was performed using Rietveld crystal and microstructure refinements from time-of-flight neutron diffraction data, with a focus on evolution of lattice parameter, atom ordering, unit cell volume, and weight fractions during the thermal cycling. Disordered δ-UZr 2 and residual γ-(U,Zr) phase are retained in the field of δ of the U-Zr equilibrium phase diagram for the U-50Zr sample, and in the field between δ and α-U for the U-35Zr sample. The α phase that is present in the reported phase diagrams of U-Zr was not observed in the diffraction patterns. The evolutions of lattice parameter and unit cell volume of δ and γ are affected by both thermal expansion and chemistry.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Magnetic ordering suppressed phase transformation of a TRIP-HEA during thermal cycling
Transformation-induced plasticity (TRIP) high-entropy alloys (HEAs) have drawn great attention as they present excellent mechanical properties, and their phase stability is critical for the underlying deformation mechanisms and the application temperature range. In this study, the kinetic phase transformation behavior of a dual-phase TRIP-HEA Fe 50 Mn 30 Co 10 Cr 10 (at. %) was probed by in situ neutron diffraction during thermal cycling between 293 and 425 K. Continuous austenitic and martensitic transformation were visualized through the evolution of hexagonal close-packed phase fraction during thermal cycling. Specifically, thanks to the magnetic sensitivity of neutron diffraction, it was found that the martensitic transformation under cooling became suppressed when the antiferromagnetic ordering started at ~326 K. This temperature was further confirmed as the Néel temperature by magnetization measurements. In this work, thermodynamic calculations revealed that the suppression effect on martensitic transformation is attributed to the consumption of the chemical driving force by the magnetic ordering. The magnetic ordering at such relatively high temperature is associated with the high Mn content. These findings shed light on a potential strategy to achieve better mechanical properties of Mn-containing alloys by manipulating the magnetic property through tuning the Mn content.
36 MATERIALS SCIENCE↗
PIP-II cryoplant non thermal cycling updates
The Proton Improvement Plan-II (PIP-II) is a crucial upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (LINAC) with 23 cryomodules operating at 2 K. The LINAC thermohydraulic conditions are satisfied by the cryogenic subsystems: Cryogenic Distribution System (CDS), a helium refrigerator cold box (CB), a warm compression station (WCS) and a helium recovery system (RSYS). The accelerator has a strict requirement of non-thermal cycling of the LINAC cryomodules during planned and unplanned subsystem outages. This paper presents an integrated reliability analysis of the PIPII cryoplant. The study evaluates both normal and abnormal operating modes, with a focus on identifying integrated scenarios that put subsystems components under stress. The conclusions of this study will help build redundancy to mitigate LINAC thermal cycling risks during planned and unplanned subsystem outages.
43 PARTICLE ACCELERATORS↗
Thermal cycling induced alteration of the stacking order and spin-flip in the room temperature van der Waals magnet Fe 5 GeTe 2
The magnetic properties of the quasi-two-dimensional van der Waals magnet Fe 5–δ GeTe 2 (F5GT), which has a high ferromagnetic ordering temperature T C ~315 K, remain to be better understood. It has been demonstrated that the magnetization of F5GT is sensitive to both the Fe deficiency δ and the thermal-cycling history. Here, we investigate the structural and magnetic properties of F5GT single crystals with a minimal Fe deficiency (|δ |≤ 0.1), utilizing combined x-ray and neutron scattering techniques. Herein our study reveals that the quenched F5GT single crystals experience an irreversible, first-order transition at T S ~110 K upon first cooling, where the stacking order partly or entirely converts from ABC-stacking order to AA-stacking order. Importantly, the magnetic properties, including the magnetic moment direction and the enhanced T C after the thermal cycling, are intimately related to the alteration of the stacking order. Our work highlights the significant influence of the lattice symmetry to the magnetism in F5GT.
2-dimensional systems↗
PIPII cryoplant non thermal cycling updates
The Proton Improvement Plan-II (PIP-II) is a crucial upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (LINAC) with 23 cryomodules operating at 2K. The LINAC thermohydraulic conditions are satisfied by the cryogenic subsystems: Cryogenic Distribution System (CDS), a helium refrigerator cold box (CB), a warm compression station (WCS) and a helium recovery system (RSYS). The accelerator has a strict requirement of non-thermal cycling of the LINAC cryomodules during planned and unplanned subsystem outages. This paper presents an integrated operating modes analysis of the of the LINAC/CDS thermohydraulic loads satisfied by the CB/WCS cooling system supported by the RSYS inventory management system. The study is based on latest cryoplant and CDS engineering deliverables, as well as the recent performance data from single cryomodule qualification tests performed at the Fermilab PIP-II Injector Test test s tand. The study evaluates both normal and abnormal operating modes, with a focus on identifying integrated scenarios that put subsystems components under stress. The conclusions of this study will help build redundancy to reduce the risk of thermal cycles during planned and unplanned subsystem outages.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Inelastic Deformation in Methylammonium Lead Iodide Perovskite and Mitigation by Additives during Thermal Cycling
Metal halide perovskite thin films are promising materials for next-generation photovoltaic applications, but the thermomechanical instabilities of these materials are critical barriers to device longevity. In this study, we measure the evolution of stresses in methylammonium lead iodide (MAPbI3) films thermally cycled from 25 to 105 °C using a multibeam optical stress sensor (MOSS) system. We demonstrate that these films undergo residual stress buildup due to inelastic deformation as well as a simple mitigation strategy by incorporating low concentrations of 5-aminovaleric acid hydrochloride (5-AVACl) as an additive. Adding 5-AVACl increases the tensile stresses measured at room temperature but beneficially decreases the biaxial modulus from 9.60 ± 0.44 GPa to 7.95 ± 0.55 GPa, resulting in greater accommodation of thermal stresses. The hysteresis loop is ~63% smaller with the inclusion of 5-AVACl, and the stress relaxation at 50 °C decreases from 86.46 to 51.49 MPa. The larger stress relaxation in pristine MAPbI 3 is correlated with grain boundary opening after five cycles, while the inclusion of 5-AVACl mitigates this degradation. Furthermore, our findings underscore the importance of studying the dynamic response of perovskite films during thermal cycling and lay the foundation for further exploration into the mechanisms governing the thermomechanical behavior of perovskite thin films.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Thermo-chemo-mechanical understanding of damage development in porous cementitious materials exposed to sodium chloride under thermal cycling
Interactions between sodium chloride (NaCl) and cementitious materials have shown to facilitate premature deteriorations of concrete in cold environments. NaCl chemically interacts with tri‑calcium aluminate (C{sub 3}A) and monosulfate (AF{sub m}) resulting in a chemical phase change during thermal cycling. The chemical phase change can create damage in porous cementitious materials. Experimental and thermodynamic modeling were conducted in this study to understand the thermo-chemo-physical interactions between NaCl and cementitious materials and identify the source of the chemical phase change. Results indicates that the destructive chemical phase change is the formation of mirabilite (Na{sub 2}SO{sub 4}.10H{sub 2}O). It was found that the phase change temperature of mirabilite is strongly influenced by the concentration of NaCl in the solution. At high concentration NaCl solutions (>10% by mass), mirabilite is formed due to the release of a small amount of sulfate ions from the concrete matrix.
36 MATERIALS SCIENCE↗