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Type Buchenauer, D.A.; Karnesky, R.A.; Fang, Z.Z.; Ren, C.; Oya, Y.; Otsuka, T.; Yamauchi, Y.; Whaley, J.A.
  Publication Gas-driven permeation of deuterium through tungsten and tungsten alloys Volume Journal Article
Pages 2016
  Abstract Fusion Engineering and Design  
  Corporate Author  
Publisher 109-111  
Editor Part A
  Summary Language 104-108 Series Editor Iter; permeation; Plasma facing component; Tungsten; Tungsten alloy  
Abbreviated Series Title To address the transport and trapping of hydrogen isotopes, several permeation experiments are being pursued at both Sandia National Laboratories (deuterium gas-driven permeation) and Idaho National Laboratories (tritium gas- and plasma-driven tritium permeation). These experiments are in part a collaboration between the US and Japan to study the performance of tungsten at divertor relevant temperatures (PHENIX). Here we report on the development of a high temperature (<=1150 °C) gas-driven permeation cell and initial measurements of deuterium permeation in several types of tungsten: high purity tungsten foil, ITER-grade tungsten (grains oriented through the membrane), and dispersoid-strengthened ultra-fine grain (UFG) tungsten being developed in the US. Experiments were performed at 500-1000 °C and 0.1-1.0 atm D2 pressure. Permeation through ITER-grade tungsten was similar to earlier W experiments by Frauenfelder (1968-69) and Zaharakov (1973). Data from the UFG alloy indicates marginally higher permeability (< 10×) at lower temperatures, but the permeability converges to that of the ITER tungsten at 1000 °C. The permeation cell uses only ceramic and graphite materials in the hot zone to reduce the possibility for oxidation of the sample membrane. Sealing pressure is applied externally, thereby allowing for elevation of the temperature for brittle membranes above the ductile-to-brittle transition temperature.
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0920-3796 no NU @ karnesky @ 11514
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Causey, Rion A.; Karnesky, Richard A.; San Marchi, Chris Tritium Barriers and Tritium Diffusion in Fusion Reactors Book Chapter 2012 Comprehensive Nuclear Materials 4.16 511-549 arriers, carbides, deuterium, diffusion, first wall materials, fusion, hydrogen, metals, nitrides, oxides, permeation, recombination, solubility, structural materials, tritium Tritium and deuterium induce radiation in reactor materials and some radioactive tritium gas may be released. Most of the materials used in fusion reactors are metals that have relatively high permeabilities for tritium. The fusion community has been working on barriers to minimize tritium release. Unfortunately, most barrier materials work very well during laboratory experiments, but fail to meet requirements when placed in radiation environments. This chapter presents tritium permeation characteristics of various materials used in fusion reactors, including plasma-facing, structural, and barrier materials. The necessary parameters for tritium release calculations for various regions of a fusion reactor are given. Elsevier Amsterdam Konings, Rudy J. M.; Stoller, Roger. E. 008056027X no NU @ karnesky @ 10704
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Chao, Paul; Karnesky, Richard A. Hydrogen Isotope trapping in Al-Cu binary alloys Journal Article 2016 Materials Science & Engineering A Mater Sci Eng A 658 422-428 Age-hardening, Aluminium alloys, Al-Cu, Hydrogen diffusion and trapping, Hydrogen desorption The trapping mechanisms for hydrogen isotopes in Al-X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al-Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ&#8729;mol-1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high; for Al-2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15x10-7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample. no NU @ karnesky @ 11513
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Dingreville, R.; Karnesky, R.A.; Puel, G.; Schmitt, J.-H. Synergies between computational modeling and experimental characterization of materials across length scales Journal Article 2015 Journal of Materials Science 51 3 1176-1177 Springer US English 0022-2461 no NU @ karnesky @ 11512
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Dingreville, Rémi; Karnesky, Richard A.; Puel, Guillaumel; Schmitt, Jean-Hubert Review of the Synergies Between Computational Modeling and Experimental Characterization of Materials Across Length Scales Journal Article 2015 Journal of Materials Science 51 3 1178-1203 Coupling experiments and modeling; Multiscale modeling; Integrated computationalmaterials Engineering (ICME); 3D microstructure characterization; Characterization methods With the increasing interplay between experimental and computational approaches at multiple length scales, new research directions are emerging in materials science and integrated computational mechanics. Such cooperative interactions find many applications in the development, characterization and design of complex material systems. This manuscript reports recent trends where predictive modeling capabilities are developed in conjunction with experiments and advanced characterization to gain a greater insight into structure-properties relationships and study various physical phenomena and mechanisms. After a general discussion on the perspective from various communities, the article focuses on the latest experimental and theoretical opportunities. Emphasis is given to the role of experiments in multiscale models, including insights into how computations can be used as discovery tools for materials engineering, rather than to "simply" support experimental work. This is illustrated by examples from several application areas on structural materials. This manuscript ends with a discussion on some of the problems and open scientific questions that are being explored in order to advance this relatively new field of research forward. no NU @ karnesky @ 11510
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Karnesky, R.A.; Chao, P.; Buchenauer, D.A. Hydrogen isotope permeation and trapping in additively manufactured steels Conference Article 2017 ASME Pressure Vessels and Piping Conference 6A V06AT06A019 Additively manufactured (AM) austenitic stainless steels are intriguing candidates for the storage of gaseous hydrogen isotopes. Complex vessel geometries can be built more easily than by using conventional machining options. Parts built with AM steel tend to have excellent mechanical properties (with tensile strength, ductility, fatigue crack growth, and fracture toughness comparable to or exceeding that of wrought austenitic stainless steel). However, the solidification microstructures produced by AM processing differ substantially from the microstructures of wrought material. Some features may increase permeability, including both some amount of porosity and a greater amount of ferrite. Because the diffusivity of hydrogen in ferrite is greater than in austenite (six orders of magnitude at ambient temperature), care must be taken to retain the performance that is taken for granted due to the base alloy chemistry. Furthermore, AM parts tend to have greater dislocation densities and greater amounts of carbon, nitrogen, and oxygen. These features, along with the austenite/ferrite interfaces, may contribute to greater hydrogen trapping. We report the results of our studies of deuterium transport in various austenitic (304L, 316, and 316L) steels produced by AM (via either powder bed fusion or blown powder methods). The hydrogen permeability (an equilibrium property) changes negligibly (less than a factor of 2), regardless of chemistry and processing method, when tested between 150 and 500 °C. This is despite increases in ferrite content up to FN=2.7. However, AM materials exhibit greater hydrogen istotope trapping, as measured by permeation transients, thermal desorption spectra, and inert gas fusion measurement. The trapping energies are likely modest (<10 kJ/mol), but may indicate a larger population of trap sites than in conventional 300-series steels. ASME no NU @ karnesky @ karnesky_hydrogen_2017 11517
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Karnesky, Richard A. Mechanical Properties and Microstructure of Al–Sc with Rare-Earth Element or Al[sub:2]O[sub:3] Additions Book Whole 2007 258 Al-Sc Aluminum alloys strengthened with coherent (L1[sub:2]), nanosize Al[sub:3]Sc precipitates are structural materials that have outstanding strength at ambient and elevated temperatures. They are creep resistant at 300 °C and exhibit a threshold stress, below which creep is not measurable. Introducing ternary alloying additions, such as rare-earth elements (RE=Y, Dy, Er), that segregate within Al[sub:3]Sc precipitates improves this creep resistance by increasing the lattice parameter misfit of precipitates with Al. In this thesis, Al–600 Sc–200 RE and Al–900 Sc–300 Er (at. ppm) are studied. These elements are an order of magnitude less expensive than Sc, so reduce alloy costs. As an alternative or supplement to ternary additions, submicron (incoherent) Al[sub:2]O[sub:3] dispersoids impart additional strengthening. The dispersion-strengthened cast alloys, DSC–Al–1100 Sc and DSC–Al–800 Sc–300 Zr, studied in this thesis contain 30 vol.% Al[sub:2]O[sub:3]. In this thesis, the temporal evolution of Al–Sc–RE and DSC–Al–Sc(–Zr) alloys are measured using Local-Electrode Atom-Probe (LEAP) tomography, conventional transmission electron microscopy, and electrical conductivity. These techniques measure the changes in precipitate number density, size, volume fraction, chemical composition, and interprecipitate distance and are compared to models. They are also employed to measure the diffusivity and solid solubility of Er in Al in Al–300 Er, Al–450 Er, and Al–600 Er. The mechanical behavior (microhardness, yield, and creep) of the alloys is studied at 25, 300, and 350 °C. The effect of Al[sub:3](Sc[sub:1-x]Er[sub:x]) precipitate size and interprecipitate distance is studied by varying isochronal and isothermal aging treatments. Various models and simulations are compared to experimental data. At ambient temperatures, very small Al[sub:3](Sc[sub:1-x]M[sub:x]) precipitates contribute to order strengthening and larger (unshearable) precipitates are bypassed by dislocations through Orowan bowing. Dislocation dynamics simulations allow both processes to operate in a glide plane, where precipitate distributions may be gathered directly or be informed by LEAP tomography data. At elevated temperatures, the lattice parameter and modulus mismatches of Al[sub:3](Sc[sub:1-x]M[sub:x]) oppose both dislocation climb over Al[sub:3](Sc[sub:1-x]M[sub:x]) and dislocation detachment from Al[sub:2]O[sub:3]. Northwestern University Ph.D. thesis Evanston, IL English no NU @ karnesky @ 10000
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Karnesky, Richard A.; Bartelt, Norman C.; Huang, Derek; Teslich, Nick; Kumar, Mukul Imaging and Quantification of Hydrogen Isotope Trapping Report 2012 SAND2012-8539 The location of hydrogen isotopes is imaged in austenitic stainless steel and model materials using local-electrode atom-probe (LEAP) tomography and trapping energies are measured by thermal desorption spectroscopy. LEAP tomography has sub-nanometer resolution and excellent compositional sensitivity due to pulse counting techniques. Site-specific sample preparation is possible using focused-ion beam, enabling us to show trapping at low density features, such as grain boundaries in a model materials (commercially pure nickel and ultra-fine-grain Al-Mg). LEAP tomography is the only known technique to measure trapping to solute atoms (here, nitrogen in 21Cr-6Ni-9Mn austenitic stainless steel), and this report is the first use of the technique to image trapping in austenitic stainless steels. The experimental work is compared with first-principles calculations of the binding energy of hydrogen isotopes to solid solution nitrogen in stainless steels. no NU @ karnesky @ 11509
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Karnesky, Richard A.; Dunand, David C.; Seidman, David N. Evolution of Nanoscale Precipitates in Al Microalloyed with Sc and Er Journal Article 2009 Acta Materialia Acta Mater. 57 14 4022-4031 Aluminum alloys; Rare-earth elements; Scandium; Precipitation; Coarsening; Al-Sc-Er The coarsening kinetics of nanoscale, coherent Al[sub:3](Sc[sub:1-x]Er[sub:x]) precipitates in [alpha]–Al during aging of a supersaturated Al–0.06 Sc–0.02 Er (at.%) alloy at 300 °C are studied using transmission electron microscopy and local-electrode atom-probe tomography. Erbium and Sc segregate at the precipitate core and shell, respectively. The matrix supersaturations of Er and Sc, as well as the mean precipitate radius and number density evolve in approximate agreement with coarsening models, allowing the determination of the matrix/precipitate interfacial free energy and solute diffusivities. At 300 °C, the [alpha]–Al/Al[sub:3](Sc[sub:1-x]Er[sub:x]) interfacial free energy due to Sc is about twice as large as for [alpha]–Al/Al[sub:3]Sc. The diffusivity of Er in the ternary alloy is about three orders of magnitude smaller than that of Er in binary Al–0.045 at.% Er and about two orders of magnitude smaller than the diffusivity of Sc in binary Al–Sc. The measured Sc diffusivity is consistent with literature values. no NU @ karnesky @ 10599
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Karnesky, Richard A.; Isheim, Dieter ; Seidman, David N. Direct Measurement of 2-Dimensional and 3-Dimensional Interprecipitate Distance Distributions from Atom-Probe Tomographic Reconstructions Journal Article 2007 Applied Physics Letters Appl. Phys. Lett. 91 1 013111:1-3 Interprecipitate distance distributions; Atom-probe tomography; Precipitation; Ferritic steels Edge-to-edge interprecipitate distance distributions are critical for predicting precipitation strengthening of alloys and other physical phenomena. A method to calculate this 3-Dimensional distance and the 2-Dimensional interplanar distance from atom-probe tomographic data is presented. It is applied to nanometer-sized Cu-rich precipitates in an Fe-1.7 at.% Cu alloy. Experimental interprecipitate distance distributions are discussed. no NU @ karnesky @ 1911
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