The Experts below are selected from a list of 3117 Experts worldwide ranked by ideXlab platform
T Muroga - One of the best experts on this subject based on the ideXlab platform.
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effects of dispersion particle agents on the hardening of v 4cr 4ti Alloys
Journal of Nuclear Materials, 2014Co-Authors: P F Zheng, T Muroga, J M Chen, Takuya Nagasaka, Jijun Zhao, H Chen, X R DuanAbstract:Abstract In the mechanical alloying (MA) of Vanadium Alloys, various particles can have a combined dispersion-strengthening effect. The nature, especially the thermal stability, of the dispersion particle agents can play an important role for the strengthening at elevated temperatures. In order to optimize the particle species in dispersion strengthened Vanadium Alloys for high temperature application, this study focuses on the hardening of V–4Cr–4Ti alloy by different dispersion particle agents such as yttrium compounds and carbides. Alloying degrees, grain sizes, densifications and solid solution of interstitial impurities are compared for better understanding the hardening due to nano-particles. Though the dissolution of carbides may be poor, it has been found that the hardening due to Ti3SiC2 addition is efficient and most stable after annealing at high temperature up to 1723 K.
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present status of Vanadium Alloys for fusion applications
Research Papers in Economics, 2014Co-Authors: T Muroga, J M Chen, V M Chernov, Richard J Kurtz, Le M FlemAbstract:Abstract Vanadium Alloys are advanced options for low activation structural materials. After more than two decades of research, V–4Cr–4Ti has been emerged as the leading candidate, and technological progress has been made in reducing the number of critical issues for application of Vanadium Alloys to fusion reactors. Notable progress has been made in fabricating alloy products and weld joints without degradation of properties. Various efforts are also being made to improve high temperature strength and creep-rupture resistance, low temperature ductility after irradiation, and corrosion resistance in blanket conditions. Future research should focus on clarifying remaining uncertainty in the operating temperature window of V–4Cr–4Ti for application to near to middle term fusion blanket systems, and on further exploration of advanced materials for improved performance for longer-term fusion reactor systems.
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effects of grain size on high temperature creep of fine grained solution and dispersion hardened v 1 6y 8w 0 8tic
Journal of Nuclear Materials, 2011Co-Authors: T Furuno, T Muroga, Takuya Nagasaka, H Kurishita, A Nishimura, Tatsuaki Sakamoto, Sengo Kobayashi, Kiyomichi Nakai, S Matsuo, H ArakawaAbstract:Abstract Creep resistance is the major concern of Vanadium and its Alloys for fusion reactor structural applications. In order to elucidate the effects of grain size on the creep behavior of solution and dispersion strengthened Vanadium Alloys, V–1.6Y–8W–0.8TiC specimens with fine grain sizes from 0.58 to 1.45 μm were prepared by mechanical alloying and HIP without any plastic working and tested at 1073 K and 250 MPa in vacuum. It is shown that the creep resistance of V–1.6Y–8W–0.8TiC depends strongly on grain size and increases with increasing grain size: The creep life for the grain size of 1.45 μm is almost one order longer than that of 0.58 μm, and about two orders longer than that of V–4Cr–4Ti (NIFS-Heat 2) although the grain size of V–4Cr–4Ti is as large as 17.8 μm. The observed creep behavior is discussed in terms of grain size effects on dislocation glide and grain boundary sliding.
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overview of the Vanadium alloy researches for fusion reactors
Journal of Nuclear Materials, 2011Co-Authors: J M Chen, V M Chernov, Richard J Kurtz, T MurogaAbstract:Abstract Various Vanadium Alloys are being developed as one of the options of structural materials for advanced blankets of fusion reactors. Besides the large heats made in Japan and US, a 110 kg V–4Cr–4Ti ingot was produced in RF recently. Development of advanced Vanadium Alloys were also carried out, such as the ultra-fine grain Alloys containing Y and that with W and TiC strengthening particles. Investigations were performed for further widening of temperature and mechanical application windows of the reference V–4Cr–4Ti alloy by plastic deformation and heat treatments. Neutron irradiation effects combined with lithium corrosion were studied. In addition, some efforts are oriented to issues related to DEMO blanket manufacturing technology, such as W coating for first wall protection and the welding technologies to fabricate large Vanadium component. This paper highlights the recent activities of these Vanadium alloy researches, discusses the critical issues and summarizes the remaining issues to be addressed.
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review of advances in development of Vanadium Alloys and mhd insulator coatings
Journal of Nuclear Materials, 2007Co-Authors: T Muroga, J M Chen, V M Chernov, Richard J Kurtz, Takuya Nagasaka, Kenichi Fukumoto, Manabu Satou, David T Hoelzer, Bruce A Pint, Atsuyuki SuzukiAbstract:Recent progress in the development of low activation Vanadium Alloys and MHD insulator coatings for a Li-self cooled blanket is reviewed. Research progress in Vanadium Alloys is highlighted by technology for fabricating creep tubes, comparison of thermal creep in vacuum and Li, understanding impurity transfer between Vanadium Alloys and Li and its impact on mechanical properties, behavior of hydrogen and hydrogen isotopes, low dose irradiation effects on weld joints, and exploration for advanced Vanadium Alloys. Major remaining issues for Vanadium Alloys are thermal and irradiation creep, helium effects on high-temperature mechanical properties and radiation effects on low-temperature fracture properties. Er2O3 showed good compatibility with Li, and is promising as a MHD insulator coating on Vanadium Alloys. Significant progress in coating technology for this material has been made. Recent efforts are focused on multi-layer and in-situ coatings. Tests under flowing lithium conditions with a temperature gradient are necessary for quantitative examination of coating performance.
Kjeld Soballe - One of the best experts on this subject based on the ideXlab platform.
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effects of as cast and wrought cobalt chrome molybdenum and titanium aluminium Vanadium Alloys on cytokine gene expression and protein secretion in j774a 1 macrophages
European Cells & Materials, 2007Co-Authors: Stig Storgaard Jakobsen, Agnete Larsen, Meredin Stoltenberg, Jens M Bruun, Kjeld SoballeAbstract:Insertion of metal implants is associated with a possible change in the delicate balance between pro- and antiinflammatory proteins, probably leading to an unfavourable predominantly pro-inflammatory milieu. The most likely cause is an inappropriate activation of macrophages in close relation to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) Alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines [TNF-α, IL-6, IL-1α, IL-1β, IL-10] and proteins known to induce proliferation [M-CSF], chemotaxis [MCP-1] and osteogenesis [TGF-β, OPG] were determined by ELISA and Real Time reverse transcriptase – PCR (Real Time rtPCR). Lactate dehydrogenase (LDH) was measured in the medium to asses the cell viability. Surface properties of the discs were characterised with a profilometer and with energy dispersive X-ray spectroscopy. We here report, for the first time, that the prosthetic material surface (nonphagocytable) of as-cast high carbon CoCrMo reduces the pro-inflammatory cytokine IL-6 transcription, the chemokine MCP-1 secretion, and M-CSF secretion by 77 %, 36 %, and 62 %, respectively. Furthermore, we found that reducing surface roughness did not affect this reduction. The results suggest that as-cast CoCrMo alloy is more inert than wrought CoCrMo and wrought TiAlV Alloys and could prove to be a superior implant material generating less inflammation which might result in less osteolysis.
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effects of as cast and wrought cobalt chrome molybdenum and titanium aluminium Vanadium Alloys on cytokine gene expression and protein secretion in j774a 1 macrophages
European Cells & Materials, 2007Co-Authors: Stig Storgaard Jakobsen, Agnete Larsen, Meredin Stoltenberg, Jens M Bruun, Kjeld SoballeAbstract:Insertion of metal implants is associated with a possible change in the delicate balance between pro- and anti-inflammatory proteins, probably leading to an unfavourable predominantly pro-inflammatory milieu. The most likely cause is an inappropriate activation of macrophages in close relation to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) Alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines (TNF-alpha, IL-6, IL-alpha, IL-1beta, IL-10) and proteins known to induce proliferation (M-CSF), chemotaxis (MCP-1) and osteogenesis (TGF-beta, OPG) were determined by ELISA and Real Time reverse transcriptase - PCR (Real Time rt-PCR). Lactate dehydrogenase (LDH) was measured in the medium to asses the cell viability. Surface properties of the discs were characterised with a profilometer and with energy dispersive X-ray spectroscopy. We here report, for the first time, that the prosthetic material surface (non-phagocytable) of as-cast high carbon CoCrMo reduces the pro-inflammatory cytokine IL-6 transcription, the chemokine MCP-1 secretion, and M-CSF secretion by 77%, 36%, and 62%, respectively. Furthermore, we found that reducing surface roughness did not affect this reduction. The results suggest that as-cast CoCrMo alloy is more inert than wrought CoCrMo and wrought TiAlV Alloys and could prove to be a superior implant material generating less inflammation which might result in less osteolysis.
H Matsui - One of the best experts on this subject based on the ideXlab platform.
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development of irradiation capsules in liquid metal environment in joyo and their application to irradiation creep measurement of Vanadium Alloys
Journal of Nuclear Science and Technology, 2008Co-Authors: Kenichi Fukumoto, H Matsui, Minoru Narui, Kazuhiro Ito, Yasuhide YanoAbstract:In order to perform irradiation experiments in a liquid metal environment in a nuclear reactor, an irradiation technique with sodium bonding irradiation capsules was developed and a series of neutron irradiation experiments with sodium bonding irradiation capsules were performed in Joyo. The design and fabrication of sodium bonding capsules, sodium filling into capsules, capsule loading to Joyo, irradiation experiments, dismantling for irradiated capsules, removing the irradiated specimens from sodium-filled capsules, and sodium cleaning of the irradiated specimens were established through this study. Using the Joyo irradiation with the sodium bonding capsules where irradiation temperature was distributed uniformly, the irradiation creep experiment for highly purified V-4Cr-4Ti Alloys, NIFS-Heat, was carried out and the knowledge about the irradiation creep behavior of the Alloys was obtained.
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irradiation induced precipitates in Vanadium Alloys studied by atom probe microanalysis
Journal of Nuclear Materials, 2007Co-Authors: N Nita, H Matsui, Y Anma, T Ohkubo, K HonoAbstract:Abstract Radiation-induced titanium precipitates are a major cause of irradiation hardening in Vanadium Alloys, but microstructural information is still far from comprehensive. In particular, the nature of black dot clusters observed to form during irradiation at low temperatures is still not clear while the large size Ti-precipitates with platelet shapes are relatively well characterized. V–4Cr–(0.1, 1 and 3 wt%)Ti Alloys were irradiated up to 0.2 dpa at 350 °C. In TEM observations, platelet precipitates on {1 0 0} planes were observed in V–4Cr–3Ti and V–4Cr–1Ti, while a high density of small defect clusters was observed as black dot contrast in V–4Cr–1Ti. Enrichment of titanium as well as oxygen and titanium oxide in the matrix were observed by three-dimensional atom probe microanalysis in all Alloys. Small clusters with sphere shape were observed in V–4Cr–0.1Ti, while the platelet morphology was seen in the other Alloys. The mechanisms of nucleation and growth of precipitates in Vanadium Alloys are discussed.
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irradiation induced precipitates in Vanadium Alloys studied by atom probe microanalysis
Journal of Nuclear Materials, 2007Co-Authors: N Nita, H Matsui, Y Anma, T Ohkubo, K HonoAbstract:Abstract Radiation-induced titanium precipitates are a major cause of irradiation hardening in Vanadium Alloys, but microstructural information is still far from comprehensive. In particular, the nature of black dot clusters observed to form during irradiation at low temperatures is still not clear while the large size Ti-precipitates with platelet shapes are relatively well characterized. V–4Cr–(0.1, 1 and 3 wt%)Ti Alloys were irradiated up to 0.2 dpa at 350 °C. In TEM observations, platelet precipitates on {1 0 0} planes were observed in V–4Cr–3Ti and V–4Cr–1Ti, while a high density of small defect clusters was observed as black dot contrast in V–4Cr–1Ti. Enrichment of titanium as well as oxygen and titanium oxide in the matrix were observed by three-dimensional atom probe microanalysis in all Alloys. Small clusters with sphere shape were observed in V–4Cr–0.1Ti, while the platelet morphology was seen in the other Alloys. The mechanisms of nucleation and growth of precipitates in Vanadium Alloys are discussed.
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effects of interstitial impurity on behavior of helium defect complexes in Vanadium studied by thds
Journal of Nuclear Materials, 2007Co-Authors: N Nita, K Miyawaki, H MatsuiAbstract:Abstract The effects of helium on macroscopic mechanical properties in Vanadium Alloys have been studied rather extensively. However, the evolution processes of helium-defect complexes, especially during the early stage, is not clearly understood. This is mainly because of the complexity of helium behavior due to the large amount of interstitial impurities (C, N, O, etc.) in Vanadium. THDS (thermal helium desorption spectrometry) was performed to examine the nature and behavior of helium-defect complexes. The observed desorption peaks were assumed to be concerned with vacancy type defects. In Vanadium, most of vacancies are decorated by interstitial impurities, and implanted helium produces HenVnX-type defects (X = C, N, O). The desorption peaks of 570 K, 690 K and 940 K were assigned as HenOV, HenOV2 and HenOV4, respectively. The population of these peaks increased with oxygen concentration. On the other hand, some peaks which were independent of impurity concentration were deduced as impurity free defect clusters such as HenVn.
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recent progress on development of Vanadium Alloys for fusion
Journal of Nuclear Materials, 2004Co-Authors: Richard J Kurtz, T Muroga, V M Chernov, H Matsui, David T Hoelzer, K Abe, G R OdetteAbstract:Considerable progress has been made toward development of Vanadium Alloys for fusion. Much of the recent research has focused on Vanadium Alloys containing 4-5% Cr and 4-5% Ti, but a number of alternative compositions and processing routes have been explored in an effort to achieve improved performance. The goal of this paper is to review significant new results and to highlight critical issues that remain for future research. Progress in understanding the influence of interstitial impurities on microstructural evolution in both thermal and radiation environments are covered. The current state of knowledge of hardening and embrittlement of Vanadium Alloys in response to neutron irradiation is reviewed. Atomic-scale computer simulations to elucidate fundamental irradiation damage mechanisms are presented. The thermal and irradiation creep behavior of V-4Cr-4Ti is summarized along with an overview of the effects of He on tensile properties.
D.l. Smith - One of the best experts on this subject based on the ideXlab platform.
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Vanadium Alloys overview and recent results
Journal of Nuclear Materials, 2002Co-Authors: T Muroga, D.l. Smith, V M Chernov, Takuya Nagasaka, H Matsui, K Abe, S J ZinkleAbstract:Abstract This paper reviews recent progress in research on Vanadium Alloys with emphasis on V–4Cr–4Ti as a reference composition. New high purity V–4Cr–4Ti ingots and products (NIFS-HEATs) were made. The improved purity of the Alloys made a practical demonstration of enhanced feasibility of recycling as a method of handling after use in fusion reactors. Significant progress has been made in the understanding of physical metallurgy of V–4Cr–4Ti and effects of O, N and C on the alloy properties such as low and high temperature mechanical properties, welding properties and low temperature irradiation effects, by means of including the comparison of various large heats and model Alloys with different impurity levels. The effects of other trace impurities on some of the properties are also discussed. Other current efforts to characterize V–4Cr–4Ti, to improve its properties and to explore advanced Vanadium Alloys are reviewed. Issues remaining for the future investigations are discussed.
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critical issues and current status of Vanadium Alloys for fusion energy applications
Journal of Nuclear Materials, 2000Co-Authors: Richard J Kurtz, D.l. Smith, T Muroga, V M Chernov, H Matsui, K Abe, G R Odette, V A Kazakov, G E Lucas, S J ZinkleAbstract:Vanadium Alloys are widely regarded as possessing desirable mechanical and physical properties for application as structural materials in fusion power systems. The bulk of the recent research on Vanadium is focussed on ternaries containing 4–5% Cr and 4–10% Ti. The aim of this paper is to review significant results generated by the international research and development community on this alloy system and to highlight the critical issues that must be resolved before alloy development can proceed to the next stage. Recent progress on understanding the physical metallurgy, fabrication and joining behavior, and compatibility with hydrogen and oxygen containing environments of unirradiated Vanadium Alloys is discussed. The effect of low-temperature neutron irradiation on mechanical properties and their relationship to the observed microstructure are briefly summarized. Current efforts to characterize the high-temperature mechanical properties, develop constitutive equations describing flow and fracture, and understand and mitigate the effects of non-metallic impurities on properties are presented.
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Development of electrically insulating coatings on Vanadium Alloys for lithium-cooled blankets
Fusion Engineering and Design, 2000Co-Authors: D.l. Smith, C. B. Reed, Krishnamurti Natesan, J.-h. Park, Richard F. MattasAbstract:The self-cooled lithium blanket concept with a Vanadium structure offers a potential for high performance with attractive safety and environmental features. Based on blanket design studies, it became apparent that electrically insulating duct walls would be required to reduce the magnetohydrodynamic (MHD) pressure drop for liquid metal-cooled blankets for high magnetic field fusion devices. As a result, development of insulator coatings was recommended as the most appropriate approach for resolving this issue. Oxides such as CaO, Y2O3. BeO. MgO, MgAl2O4, and Y3Al2O12and nitrides such as AlN, BN and Si3N2were initially considered potential candidate coating materials. Based on results of scoping studies, CaO and AlN have been selected as primary candidates for further development. Progress on the development of CaO and AlN coatings, including in-situ formation and electrical properties measurements, are summarized in this paper.
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Vanadium base Alloys for fusion first wall blanket applications
International Journal of Refractory Metals & Hard Materials, 2000Co-Authors: D.l. Smith, M C Billone, Ken NatesanAbstract:Abstract Vanadium Alloys have been identified as a leading candidate material for fusion first-wall/blanket applications. Certain Vanadium Alloys exhibit favorable safety and environmental characteristics, good fabricability, high temperature and heat load capability, good compatibility with liquid metal coolants and resistance to irradiation damage. The current focus is on Vanadium Alloys with (3–9 wt%) Cr and (3–10 wt%) Ti with a V–4Cr–4Ti alloy as the reference composition. Substantial progress has been made in the development of Vanadium Alloys for the fusion first wall/blanket applications including production and welding, characterization of baseline properties, corrosion/compatibility, and effects of irradiation on the properties. This paper presents an overview of the development of Vanadium Alloys for fusion applications and a summary of key issues requiring further research.
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research and development on Vanadium Alloys for fusion applications
Journal of Nuclear Materials, 1998Co-Authors: S J Zinkle, D.l. Smith, H Matsui, K Abe, A F Rowcliffe, E V Van Osch, V A KazakovAbstract:The current status of research and development on unirradiated and irradiated V-Cr-Ti Alloys intended for fusion reactor structural applications is reviewed, with particular emphasis on the flow and fracture behavior of neutron-irradiated Vanadium Alloys. Recent progress on fabrication, joining, oxidation behavior, and the development of insulator coatings is also summarized. Fabrication of large (>500 kg) heats of V-4Cr-4Ti with properties similar to previous small laboratory heats has now been demonstrated. Impressive advances in the joining of thick sections of Vanadium Alloys using GTA and electron beam welds have been achieved in the past two years, although further improvements are still needed.
Takuya Nagasaka - One of the best experts on this subject based on the ideXlab platform.
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effects of dispersion particle agents on the hardening of v 4cr 4ti Alloys
Journal of Nuclear Materials, 2014Co-Authors: P F Zheng, T Muroga, J M Chen, Takuya Nagasaka, Jijun Zhao, H Chen, X R DuanAbstract:Abstract In the mechanical alloying (MA) of Vanadium Alloys, various particles can have a combined dispersion-strengthening effect. The nature, especially the thermal stability, of the dispersion particle agents can play an important role for the strengthening at elevated temperatures. In order to optimize the particle species in dispersion strengthened Vanadium Alloys for high temperature application, this study focuses on the hardening of V–4Cr–4Ti alloy by different dispersion particle agents such as yttrium compounds and carbides. Alloying degrees, grain sizes, densifications and solid solution of interstitial impurities are compared for better understanding the hardening due to nano-particles. Though the dissolution of carbides may be poor, it has been found that the hardening due to Ti3SiC2 addition is efficient and most stable after annealing at high temperature up to 1723 K.
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Effect of yttrium on dynamic strain aging of Vanadium Alloys
Journal of Nuclear Materials, 2013Co-Authors: Takeshi Miyazawa, Takuya Nagasaka, Takeo Muroga, Yoshimitsu Hishinuma, Yuhki Satoh, Sawoong Kim, Hiroaki AbeAbstract:Abstract In order to improve the performance of Vanadium Alloys for fusion reactors, yttrium (Y) was added to reduce the interstitial O in the matrix by enhanced precipitation with Y. Effect of Y on interstitial C, N and O, however, remains to be investigated since they affect mechanical and fracture properties for Vanadium Alloys by pinning dislocations, such as dynamic strain aging (DSA). In this study, tensile tests were carried out on annealed V–4Cr–4Ti and V–4Cr–4Ti–Y Alloys from 473 to 1073 K at strain rates ranging from 6.67 × 10 −5 to 6.67 × 10 −1 s −1 to investigate the performance of DSA. In the case of high-purity Alloys, DSA regime was narrowed due to Y addition and the reduction in O content. In the case of O doped V–4Cr–4Ti Alloys, DSA regime was also narrowed. This may be because the enhanced Ti–O precipitation reduced the O level in the matrix. Also, coarse precipitates (
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Investigation on mechanical alloying process for Vanadium Alloys
Journal of Nuclear Materials, 2013Co-Authors: P F Zheng, Takuya Nagasaka, Takeo Muroga, J M ChenAbstract:Abstract Mechanical alloying (MA) is an efficient approach for fabricating particle-dispersion Alloys, and has recently been introduced to strengthen structural materials including Vanadium Alloys for fusion application. Dissolution behavior of the alloying elements is a key issue for optimizing MA in fabricating particle-dispersion Vanadium Alloys. This paper studies the MA process for V–4Cr–4Ti Alloys with Y addition. The result shows that, in V matrix, the dissolution rate of Y is higher than that of Cr, and the dissolution rate of Cr is higher than that of Ti. In addition, dissolution of milling ball material and dispersion particles can harden the MA-fabricated alloy.
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recent progress of tungsten r d for fusion application in japan
Physica Scripta, 2011Co-Authors: Y Ueda, H T Lee, N Ohno, Shin Kajita, Akihiko Kimura, Ryuta Kasada, Takuya Nagasaka, Y Hatano, Akira Hasegawa, H KurishitaAbstract:The status of ongoing research projects of tungsten R&D in Japan is summarized in this paper. For tungsten material development, a new improved fabrication technique, the so-called superplasticity-based microstructural modification, is described. This technique successfully improved fracture strength and ductility at room temperature. Recent results on vacuum plasma spray W coating and W brazing on ferritic steels and Vanadium Alloys are explained. Feasibility of these techniques for the manufacture of the blanket is successfully demonstrated. The latest findings on the effect of neutron damage in tungsten on T retention and on the change in mechanical and electrical properties are described. Retention characteristics for neutron-damaged W were different compared to those for ion-damaged W. Upon neutron irradiation, tungsten Alloys containing transmutation elements of W (Re and Os) show changes in properties that are different compared with those shown by pure W. The effects of mixed plasma exposure (D/He/C) are described. Both D/He and D/C mixed ion irradiations significantly affect ion-driven permeation in W. He bubble dynamics play a key role in nano-structure formation on the W surface.
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effects of grain size on high temperature creep of fine grained solution and dispersion hardened v 1 6y 8w 0 8tic
Journal of Nuclear Materials, 2011Co-Authors: T Furuno, T Muroga, Takuya Nagasaka, H Kurishita, A Nishimura, Tatsuaki Sakamoto, Sengo Kobayashi, Kiyomichi Nakai, S Matsuo, H ArakawaAbstract:Abstract Creep resistance is the major concern of Vanadium and its Alloys for fusion reactor structural applications. In order to elucidate the effects of grain size on the creep behavior of solution and dispersion strengthened Vanadium Alloys, V–1.6Y–8W–0.8TiC specimens with fine grain sizes from 0.58 to 1.45 μm were prepared by mechanical alloying and HIP without any plastic working and tested at 1073 K and 250 MPa in vacuum. It is shown that the creep resistance of V–1.6Y–8W–0.8TiC depends strongly on grain size and increases with increasing grain size: The creep life for the grain size of 1.45 μm is almost one order longer than that of 0.58 μm, and about two orders longer than that of V–4Cr–4Ti (NIFS-Heat 2) although the grain size of V–4Cr–4Ti is as large as 17.8 μm. The observed creep behavior is discussed in terms of grain size effects on dislocation glide and grain boundary sliding.
