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Nakamichi, Masaru; Kim, Jae-Hwan; Munakata, Kenzo*; Shibayama, Tamaki*; Miyamoto, Mitsutaka*
Journal of Nuclear Materials, 442(1-3), p.S465 - S471, 2013/11
Times Cited Count：12 Percentile：65.71(Materials Science, Multidisciplinary)Ito, Tatsuya*; Yamauchi, Yuji*; Hino, Tomoaki*; Shibayama, Tamaki*; Nobuta, Yuji*; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato
Journal of Nuclear Materials, 417(1-3), p.1147 - 1149, 2011/10
Times Cited Count：13 Percentile：68.51(Materials Science, Multidisciplinary)Shibayama, Tamaki*; Nakamichi, Masaru; Miyamoto, Mitsutaka*; Kuga, Noriyoshi*; Dorn, C. K.*; Knudson, T.*
Purazuma, Kaku Yugo Gakkai-Shi, 87(4), p.259 - 267, 2011/04
no abstracts in English
Yano, Yasuhide; Yamashita, Shinichiro; Otsuka, Satoshi; Kaito, Takeji; Akasaka, Naoaki; Shibayama, Tamaki*; Watanabe, Seiichi*; Takahashi, Heishichiro
Journal of Nuclear Materials, 398(1-3), p.59 - 63, 2010/03
Times Cited Count：11 Percentile：58.20(Materials Science, Multidisciplinary)The in-reactor creep rupture tests of 11Cr-0.5Mo-2W, V, Nb F/M steel were carried out in the temperature range from 823 to 943 K using Materials Open Test Assembly in the Fast Flux Test Facility and tensile and temperature-transient-to-burst specimens were irradiated in the experimental fast reactor JOYO at temperatures between 693 to 1013 K to fast neutron doses ranging from 3.5 to 102 dpa. The results of post irradiation mechanical tests showed that there was no significant degradation in tensile and transient burst strengths even after neutron irradiation below 873 K, but that there was significant degradation in both strengths at neutron irradiation above 903 K. On the other hand, the in-reactor creep rupture times were equal or greater than those of out-reactor creep even after neutron irradiation at all temperatures. This creep rupture behavior was different from that of tensile and transient burst specimens.
Nakamichi, Masaru; Shibayama, Tamaki*; Tatenuma, Katsuyoshi*; Yonehara, Kazuo
Proceedings of 9th IEA International Workshop on Beryllium Technology (BeWS-9), p.40 - 43, 2009/09
Shibayama, Tamaki*; Kishimoto, Hirotatsu*; Koyama, Akira*; Yano, Yasuhide
Materia, 47(12), P. 628, 2008/12
no abstracts in English
Mishima, Yoshinao*; Yoshida, Naoaki*; Kawamura, Hiroshi; Ishida, Kiyohito*; Hatano, Yuji*; Shibayama, Tamaki*; Munakata, Kenzo*; Sato, Yoshiyuki*; Uchida, Munenori*; Tsuchiya, Kunihiko; et al.
Journal of Nuclear Materials, 367-370(2), p.1382 - 1386, 2007/08
Times Cited Count：28 Percentile：85.23(Materials Science, Multidisciplinary)no abstracts in English
Tsuchiya, Kunihiko; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Tanaka, Satoru*; Uchida, Munenori*; Ishida, Kiyohito*; Shibayama, Tamaki*; Munakata, Kenzo*; Sato, Yoshiyuki*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(3), p.207 - 214, 2007/03
no abstracts in English
Kawamura, Hiroshi; Tsuchiya, Kunihiko; Mishima, Yoshinao*; Yoshida, Naoaki*; Munakata, Kenzo*; Ishida, Kiyohito*; Hatano, Yuji*; Shibayama, Tamaki*; Sato, Yoshiyuki*; Uchida, Munenori*; et al.
INL/EXT-06-01222, p.1 - 7, 2006/02
no abstracts in English
TiShibayama, Tamaki*; Nakamichi, Masaru*; Uchida, Munenori*; Kawamura, Hiroshi; Kinoshita, Hiroshi*; Kiyanagi, Yoshiaki*; Takahashi, Heishichiro*; Nomura, Naoyuki*
JAERI-Conf 2004-006, p.216 - 219, 2004/03
no abstracts in English
Wakai, Eiichi; Noto, Hiroyuki*; Shibayama, Tamaki*; Nakagawa, Yuki*; Ishida, Taku*; Makimura, Shunsuke*; Wakui, Takashi; Furuya, Kazuyuki*; Ando, Masami*
no journal, ,
In the fields of energy, nuclear power, high-energy accelerator target systems, nuclear fusion, and biology, radiation causes degradation of materials and equipment, and thus it is expected to create new materials with high durability and superior functionality. In this study, for Fe-, Ti-, and W-based high-entropy alloys (HEA) composed of low activation elements (Ni and Co free), Fe-based alloys were prepared by radio frequency melting, Ti-based alloys by cold crucible levitation melting, and W-based alloys by arc melting using metal powders. These materials were tested by X-ray diffraction, microstructural observation, hardness measurement, magnetic measurement, electrical resistivity measurement, scanning transmission electron microscope STEM (or TEM, SEM) and energy dispersive X-ray spectroscopy, ultrasonic measurement, and hot isostatic pressing (HIP) method. These HEAs were found to be much harder than normal alloys, and in Fe-based HEAs, the magnetic properties and related microstructural analysis showed that they have interesting characteristics such as micro magnetic domain structures. In particular, for Fe- and W-based HEAs, the changes in crystal structure, orientation, and internal microstructure caused by HIP treatment and the accompanying effects of high temperature and pressure have been found to have a significant effect on magnetic properties and material strength properties.
-phase based titanium alloysWakai, Eiichi; Ishida, Taku*; Kano, Sho*; Shibayama, Tamaki*; Sato, Koichi*; Noto, Hiroyuki*; Makimura, Shunsuke*; Furuya, Kazuyuki*; Yabuuchi, Atsushi*; Yoshiie, Toshimasa*; et al.
no journal, ,
Titanium materials have been applied to beam window materials and beam dumps in large accelerator systems because of their low specific gravity, high corrosion resistance, strength, and other advantages. As the beam power becomes higher, further improvement of irradiation resistance is required. We have investigated further the properties of titanium alloys based on the -phase, and it was found that Ti-15-3-3-3 alloys have excellent irradiation resistance when subjected to ion irradiation. In order to investigate the cause of this, microstructures and point defects in this and related materials were evaluated by TEM, positron lifetime measurement, electrical resistivity, and stress-induced changes, among others. In addition, we have recently begun to develop a prototype of a titanium-based high-entropy alloy based on -titanium, which is attracting worldwide attention and is being developed, and have also begun to evaluate the emotional properties of this alloy. We have examined the various properties of this material and found that it has considerably higher strength than conventional iron- and titanium-based materials.
Uchida, Yosuke*; Nagai, Yoshiyasu*; Suda, Takanori*; Hashimoto, Naoyuki*; Onuki, Somei*; Shibayama, Tamaki*; Yamashita, Shinichiro; Akasaka, Naoaki
no journal, ,
no abstracts in English
Yamashita, Shinichiro; Sekio, Yoshihiro; Sakaguchi, Norihito*; Shibayama, Tamaki*; Watanabe, Seiichi*; Kokawa, Hiroyuki*
no journal, ,
Recent grain boundary structure studies have shown that optimal distribution of a high frequency of coincidence site lattice boundaries and consequent discontinuity of random boundary network in the material is one of very effective methods to enhance the intergranular corrosion resistance. This advantageous property, one of important ones for structural material of nuclear reactor, can be obtained through simple thermomechanical treatment process without any change of original chemical composition. In this study, grain boundary character distribution(GBCD)-optimized Ni-based alloy (PE16) has been developed as a prospective high-performance nuclear reactor material by grain boundary engineering processing, and then tensile behavior of GBCD-optimized Ni-based alloy was investigated to evaluate the effect of grain boundary engineering processing on mechanical property. The result of tensile test at room temperature showed that tensile strength of GBCD-optimized PE16 was somewhat lower than that of as-received PE16. However, no significant change was confirmed in elongation property. Details on tensile behavior analyses would be discussed in the conference.
Yamashita, Shinichiro; Sekio, Yoshihiro; Sakaguchi, Norihito*; Shibayama, Tamaki*; Watanabe, Seiichi*; Kokawa, Hiroyuki*
no journal, ,
Toyota, Kodai; Wakai, Eiichi; Onizawa, Takashi; Shibayama, Tamaki*; Nakagawa, Yuki*
no journal, ,
no abstracts in English
-Ti alloysWakai, Eiichi; Kano, Sho*; Ishida, Taku*; Makimura, Shunsuke*; Shibayama, Tamaki*; Wakui, Takashi
no journal, ,
In this study, the irradiation behavior and microstructural changes of Ti-15V-3Al-3V-3Sn (abbreviated as Ti-15-3), one of the beta-Ti alloys among the Ti alloys, were investigated by ion irradiation in order to improve the durability performance of equipment used in irradiation environments. depth dependence, but from the present observation, it was found that dislocation loops were not observed up to a region of about 9 dpa. In addition, diffraction pattern analysis was performed to investigate the formation of omega-phase by irradiation, and it was found that the atomic arrangement was disordered due to the formation of nano-sized materials that may be precursors of omega-phase, and that the diffuse scattering streaks became stronger with increasing dpa. On the other hand, irradiation hardening of about 1 GPa was observed in the Ti-64 material under the same conditions, while almost no irradiation hardening was observed in the T-15-3 material, indicating that it has high irradiation resistance.
Wakai, Eiichi; Shibayama, Tamaki*; Noto, Hiroyuki*; Furuya, Kazuyuki*; Iwamoto, Yosuke; Wakui, Takashi; Makimura, Shunsuke*; Ishida, Taku*; Ando, Masami*; Sato, Koichi*; et al.
no journal, ,
In fields such as nuclear power and high-energy accelerator target systems, radiation causes degradation of materials and equipment, so materials with high durability and excellent functionality are expected to be created. High-entropy alloys (HEA) are expected to have high irradiation resistance and often have high strength and good ductility. In recent years, research and development is underway worldwide for various applications. In this study, Fe- and Ti-based and W-based HEAs composed of low activation elements (free of Ni and Co) were fabricated. These materials were subjected to X-ray diffraction, microstructural observation, hardness, magnetism, electrical resistance, STEM (or TEM, SEM) and EDS, ultrasonic measurements, and hot isostatic pressing (HIP). Ion irradiation, pulsed laser irradiation, and pulsed electron beam irradiation were also performed on some of the samples to investigate their response characteristics. These HEAs were much harder than normal alloys, and the magnetic properties and related microstructural analysis of Fe-based HEAs revealed that they have interesting properties such as micro magnetic domain structures. In particular, for Fe- and W-based HEAs, the changes in crystal structure, orientation, and internal microstructure induced by HIP treatment and the accompanying effects of high temperature and pressure had a significant effect on magnetic properties and material strength properties. Furthermore, the irradiation response properties of Fe-based HEAs have been characterized.
Wakai, Eiichi; Shibayama, Tamaki*; Noto, Hiroyuki*; Wakui, Takashi
no journal, ,
In this study, we fabricated a prototype iron-based high-entropy alloy (Fe-Mn-V-Cr-Al-C) composed of low activation elements (free of Ni and Co) by radio frequency melting method and evaluated its basic properties, aiming to apply it to new functional materials for high-energy accelerator target system components, nuclear reactors and fusion reactors. XRD analysis of this material revealed that it has a BCC crystal structure, in which vanadium carbide (VC) is precipitated. This material was found not only to be magnetic, but also to have a fairly small magnetic domain structure. As for the grain size, relatively small grains (about 20-50 
m) were observed despite the homogenization heat treatment at 1150
C. With regard to strength properties, the results of Vickers hardness measurements indicated that the alloy was much harder than ordinary iron alloys, slightly exceeding pure tungsten, and elastic wave velocity measurements showed that it was faster than iron-based materials and had a higher elastic modulus than stainless steel.
Wakai, Eiichi; Noto, Hiroyuki*; Shibayama, Tamaki*; Iwamoto, Yosuke; Ishida, Taku*; Sato, Koichi*; Yabuuchi, Atsushi*; Yoshiie, Toshimasa*; Takahashi, Toshiharu*; Kobayashi, Yasuhiro*; et al.
no journal, ,
In recent years, it has been reported that high-entropy alloys (HEA) have high strength but good ductility, and they are being researched and developed by cutting-edge research institutions around the world with the aim of finding various applications in progress. In this study, we considered several Fe-based, W-based, and Ti-based HEAs, excluding Co and Ni elements, in order to aim for use in high radiation fields and considering low-activation properties. These materials mainly have a bcc crystal structure and were fabricated using a melting method and their material properties were evaluated. As a result, it was found that Fe-based HEA has properties that exceed the hardness of pure W and has excellent irradiation resistance. In addition, a Ti-based HEA that can be subjected to high-temperature forging and high-temperature rolling has been found, and evaluation of the optimal heat treatment temperature is progressing. The hardness of W-based HEA increased through Hot Isostatic Pressing (HIP) treatment, and it was found to have the world's highest hardness among HEA materials.
