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Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
no journal, ,
We have been investing the correlation between the coercive force and the averaged internal structure of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets using the small-angle neutron scattering (SANS) spectrometer, SANS-J-II installed at the beam hall of the research reactor JRR-3 in Tokai. The correlation is a clue to achieve the less or Dysprosium (Dy)-free Nd-Fe-B sintered magnets with high coercivity for high-temperature application. In this talk, we report that the coercivity is very sensitive to the averaged diameter of powder and the temperature in sintering process, and that the SANS patterns on 2-dimensional position-sensitive detector (2D-PSD) are also sensitively changed following the sintering condition.
Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Sagawa, Masato*
no journal, ,
The coercive force of Nd-Fe-B sintered magnets depends on several factors. Among those factors, the coercivity is easily affected by the temperature in the so-called low-temperature annealing process. A remarkable structural change of interface between the main phase (NdFeB) and the Nd-rich phase is believed to occur at the temperature where the coercivity reaches the highest value. We performed the small-angle neutron scattering measurements to distinguish the SANS originating in nuclear structure from that in magnetic one. The external magnetic fields were applied parallel to the -axis, and were increased up to 10 kOe every 2 kOe during the measurements. Quantitative analysis of the change of scattering patterns and the magnetization process is reported at the meeting.
Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
no abstracts in English
Kurata, Yuji; Sato, Hidetomo*; Yokota, Hitoshi*; Suzuki, Tetsuya*
no journal, ,
Liquid lead-bismuth is a candidate material used for accelerator driven systems and fast reactors. Development of corrosion resistant materials in liquid lead-bismuth is one of important research subjects to realize these systems. In this study improvement of corrosion resistance of 316SS was investigated by means of aluminum powder alloy coating. Aluminum alloys were coated on 316SS using sheets made of Al, Ti and Fe powders, and laser heating. The corrosion test was conducted at 550C for 1000h in liquid lead-bismuth where oxygen concentrations were controlled to be about 510mass%. As a result of the corrosion test, it was found that Al alloy coating protected grain boundary corrosion and surface oxidation of Fe and Cr, which were significant in 316SS substrate.
Yamamoto, Masahiro*; Hayashi, Shigenari*; Ukai, Shigeharu*; Kaito, Takeji; Otsuka, Satoshi; Osaki, Satoshi*; Azuma, Tsukasa*
no journal, ,
no abstracts in English
Shintani, Tsuyoshi*; Tsukada, Yuki*; Shiraki, Atsuhiro*; Murata, Yoshinori*; Morinaga, Masahiko*; Takaya, Shigeru; Koyama, Toshiyuki*
no journal, ,
The magnetic flux density of SUS316 changes lesser than that of SUS304 during creep deformation. In this study, the reason of this difference was investigated based on system free energy. As result, it was revealed that the strain energies of both steels, which contribute to the formation of ferromagnetic bcc phase, were almost the same. Therefore, the dependency of magnetic flux density change on steel grades will be related to that activation energy for the formation of ferromagnetic phase of SUS316 is larger than that of SUS304.
Shiota, Yoshinori; Akita, Koichi; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Yokokawa, Tadaharu*; Koizumi, Yutaka*; Harada, Hiroshi*
no journal, ,
no abstracts in English
Endo, Masaki*; Sakaguchi, Norihito*; Kinoshita, Hiroshi*; Watanabe, Seiichi*; Kokawa, Hiroyuki*; Yamashita, Shinichiro; Yano, Yasuhide; Kawai, Masayoshi*
no journal, ,
no abstracts in English
Abe, Yosuke; Jitsukawa, Shiro
no journal, ,
Using the cluster dynamics (CD) simulation, the effects of the mobility of large SIA loops on the development of the microstructure are examined under cascade irradiation condition. The obtained SIA and vacancy clusters as well as the cluster size distributions depending on the damage level are compared with results by experiments in -iron. It was shown that for mobile clusters up to three, the saturation versus dose is clearly not reproduced for both SIA and vacancy cluster densities because defect clusters are continuously produced by cascade damage but large SIA clusters do not migrate and annihilated at sinks. Therefore, taking the mobility of SIA clusters of all sizes into account in CD simulation is necessary to successfully reproduce the saturation trend of SIA cluster density as a function of irradiation dose.
Sakai, Seiji; Matsumoto, Yoshihiro; Entani, Shiro; Sugai, Isamu*; Mitani, Seiji*; Takanashi, Koki; Naramoto, Hiroshi*; Maeda, Yoshihito
no journal, ,
no abstracts in English
Iwata, Noriyuki*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Abe, Fujio*; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*
no journal, ,
no abstracts in English
Toda, Yoshiaki*; Hara, Toru*; Abe, Fujio*; Kimura, Akihiko*; Kasada, Ryuta*; Inoue, Masaki; Okuda, Takanari*; Onuki, Somei*; Ukai, Shigeharu*; Fujisawa, Toshiharu*
no journal, ,
no abstracts in English
Isselin, J.*; Vogt, G.*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*; Abe, Fujio*
no journal, ,
Lee, J. H.*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*; Abe, Fujio*
no journal, ,
Dou, P.*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*
no journal, ,
Kita, Kenichiro; Narisawa, Masaki*; Nakahira, Atsushi*; Ito, Masayoshi*; Sugimoto, Masaki; Yoshikawa, Masahito
no journal, ,
no abstracts in English
Aihara, Jun; Ueta, Shohei; Motohashi, Yoshinobu*; Sawa, Kazuhiro
no journal, ,
Development of ZrC coated fuel particles for advanced high temperature gas cooled reactors. As a basic study, the ZrC coating layer has been fabricated using the bromide process at JAEA. The coated particles were annealed at around 1800 C for 1h, under which compact sintering will be done in a practical process, in order to study effects of the heat treatment on their microstructure evolution. Then the microstructures of the ZrC layers in the batch of C/Zr = 1.35 were characterized by means of TEM. Certain changes in the shape and size of voids or free carbons region caused by the heat treatment were found. After the heat treatment, the voids or free carbons region have changed from a thin layered feature into a clod like feature with diameters of 50 to 100 nm. In addition, EELS measurements were carried out in the heat treated specimen. The * peak of carbon was observed in the spectrum from free carbons or voids region, but not in the spectrum from ZrC region.
Tode, Mayumi; Harries, J.; Teraoka, Yuden; Sumimoto, Yuichi; Inoue, Keisuke; Yoshigoe, Akitaka
no journal, ,
Study of thermal desorption characteristics of native oxide layer on the surface of the hydrogen storage materials is very important. Thermal instability of native oxide layer on VCrTi and deuterated VCrTi was observed by high resolution soft X-ray synchrotron radiation photoemission spectroscopy. All experiments have been conducted at the surface chemistry experimental station (SUREAC2000) at BL23SU, SPring-8. Before thermal annealing, the satellite peak from the native oxide layer and the V-2p peak from the bulk were observed. The O-1s peak consisted of at least two components. After thermal annealing, the O-1s peak decreases and the V-2p peak increases. Deuterium implantation affected the thermal stability of the native oxide.
Yamaguchi, Masatake; Ebihara, Kenichi; Itakura, Mitsuhiro; Suzudo, Tomoaki; Kaburaki, Hideo; Kadoyoshi, Tomoko*
no journal, ,
It is not known in detail how much hydrogen atoms can be trapped in grain boundaries of metals and how much the cohesive energy (work of fracture) of grain boundary is decreased by the hydrogen trapping. From first-principles, we calculated the trapping energy of hydrogen atoms in bcc Fe Sigma 3 (111) symmetrical tilt grain boundaries and on the fracture surfaces with varying the trapping density of hydrogen. We find that hydrogen atoms can be trapped up to a high concentration in the grain boundaries and on the fracture surfaces for Fe. We also find that the trapping energy on the surface is significantly larger than that in the grain boundary. The cohesive energy of the grain boundary is decreased by hydrogen trapping by about 30% at most. Moreover, the cohesive energy can be decreased by about 70% at most if hydrogen in solid solution state moves quickly and then adsorbs onto the newly generated fracture surfaces.