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Hatakeyama, Masahiko*; Yamagata, Ichiro
no journal, ,
Modified SUS316 austenitic stainless steel (PNC316) which is used for cladding tubes of Fast Reactor. PNC316 is the alloy based on the chemical composition of SUS316 and added a small amount of P, Ti, and Nb to improve strength at elevated temperature and swelling resistance. One of swelling control mechanisms is thought the M
P type precipitates and matrix interface behave as sinks of point defect. However, a variety of precipitates are formed besides the needle shape MP type precipitates irradiated at the high temperature of about 500 
C, and it is not clear the chemical composition and the structure of them. In this study, the precipitates formed in neutron irradiated PNC316 steel is analyzed from the view point of microstructure by three dimension atom probe (3DAP) and transmission electron microscope (TEM), and the chemical compositions of them are identified.
Watanabe, Masashi; Shikama, Tatsuo*; Tachi, Yoshiaki
no journal, ,
no abstracts in English
Yamashita, Shinichiro; Kubota, Tomoki*; Oka, Hiroshi*; Hashimoto, Naoyuki*; Onuki, Somei*
no journal, ,
Correlation between microstructure and mechanical properties of neutron-irradiated modified SUS316 (PNC316) has been studied based on post irradiation examination (PIE) database since PNC316 has been accumulated most aboundant irradiation data among core structural materials for fast reactor. In this study, comparison of various PIE data, such as tensile properties, hardness measurement, metallurgy and microstructure of PNC316, has been done, indicating that irradiation hardening occurred due to frank loop nucleation and growth by irradiation at relatively low temperature (around 400C) and that precipitate coarsening occurred by irradiation at relatively high temperature (over 700C).
Nogiwa, Kimihiro; Onitsuka, Takashi; Abe, Teruyoshi; Sakakibara, Yasuhide; Nakamura, Takahisa; Horie, Kaoru
no journal, ,
no abstracts in English
Onitsuka, Takashi; Nogiwa, Kimihiro; Abe, Teruyoshi; Sakakibara, Yasuhide; Nakamura, Takahisa; Horie, Kaoru
no journal, ,
no abstracts in English
Teraoka, Yuden
no journal, ,
no abstracts in English
thermal desorption temperatureTode, Mayumi; Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka
no journal, ,
no abstracts in English
Ara, Kuniaki; Saito, Junichi
no journal, ,
no abstracts in English
Saito, Junichi; Nagai, Keiichi; Ara, Kuniaki
no journal, ,
no abstracts in English
Fukunaga, Koichi*; Nagai, Masahiko*; Ara, Kuniaki; Saito, Junichi
no journal, ,
no abstracts in English
Itami, Toshio; Ara, Kuniaki; Saito, Junichi
no journal, ,
no abstracts in English
Ioka, Ikuo; Kiuchi, Kiyoshi; Ito, Takeshi*; Takizawa, Masayuki*; Fukai, Tsuyoshi*
no journal, ,
In order to develop evaluation technology for environmentally assisted cracking, the crack susceptibility of specimens with Brinnel indentation was examined in the corrosive environment. The multiaxial stress field was formed around the indentation. The residual stress around the indentation was analyzed by three dimensional FEM. Moreover, the residual stress was measured by the X-ray diffractometer. After the corrosion test, some cracks that expanded in the direction of the diameter were observed at the tensile residual stress area. The prospect of evaluation technology for environmentally assisted cracking under the multiaxial stress field was obtained from the results.
Sueyoshi, Hitoshi*; Ishikawa, Nobuyuki*; Suzuki, Hiroshi; Akita, Koichi
no journal, ,
Experiments of cold cracking on a 980 MPa class restraint weld joint were performed and the residual stress distribution in the joint was analyzed using neutron diffraction technique. The critical conditions for the cold cracking of the weld joint was determined from the obtained results.
Aoyagi, Yoshiteru; Kaji, Yoshiyuki
no journal, ,
In this study, we develop a crystal plasticity model considering an effect of grain boundary. In order to predict increase of local critical resolved shear stress due to existence of grain boundaries, information of grain boundary as a role of dislocation sources is introduced into a hardening law of crystal plasticity. In addition, carrying out FE simulation for plastic deformation of FCC polycrystal, the stress-strain responses such as increase of yield stress due to existence of grain boundary are discussed. We investigate comprehensively the effect of dislocation behavior on the material property of nanostructured metal. The increase of yield stress and the decrease of hardening ratio with the reduction of grain size are caused by local differences on CRSS and dislocation behavior, respectively.
Tsuru, Tomohito
no journal, ,
The dislocation-grain-boundary process is fundamental to the improvement of the mechanical properties of metallic materials. This process contributes significantly to plastic deformation as well as dislocation-dislocation interactions. These lattice defects have been effectively utilized for material strengthening as determined by the Hall-Petch relationship. However, it becomes well-known that the individual defect structure plays a great role in the whole materials system. In this study, we have developed nano-mesoscale simulation methods to understand defects dynamics under deformation since these materials characteristics are derived from mesoscopic behavior.
Al
alloy on hydrogen absorption processHiguchi, Kensuke; Machida, Akihiko; Katayama, Yoshinori; Sakaki, Koji*; Kim, H.*; Nakamura, Yumiko*
no journal, ,
no abstracts in English
Kamakura, Nozomu; Takeda, Yukiharu; Yamagami, Hiroshi; Miyaoka, Hiroki*; Tsubota, Masami*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kinoshita, Toyohiko*
no journal, ,
Metal amide has been attracted much attention as a lightweight hydride being considered for high capacity hydrogen storage materials. In this research, the electronic states of the insulator alkali metal amide (KNH, NaNH) and alkaline earth metal amide (Ca(NH), Mg(NH)) are investigated by the soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS) in the total fluorescence yield mode. The localized character of the valence electrons is shown by the sharp three peak structure commonly observed in the XES spectrum of alkali metal amide. The localized character of the valence electrons is shown by the sharp peak structure commonly observed in the XES spectrum of alkali metal amide. The broadening of the N 2p states by the hybridization is observed in the XES spectrum of the alkaline earth metal amide. Decomposition temperature of the metal amide is found to relate to the character of the chemical bond observed in the XAS.
Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
no abstracts in English
at high pressures and high tempretures by 
synchrotron X-ray diffraction measurementEndo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi
no journal, ,
In this present study, we investigated the phase diagram TiH at high pressures and high temperatures was carefully investigated by means of synchrotron X-ray diffraction measurement for new titanium alloys hydrides development.
Abe, Yosuke; Jitsukawa, Shiro
no journal, ,
It is known that the presence of even a small amount of impurities in interstitial positions can have a drastic influence on the one-dimensional (1D) motion of self-interstitial atom (SIA) loops depending on temperature and thus the accumulation of radiation damage in materials. In this study, a conventional cluster dynamics (CD) model have been extended to allow 1D motion for SIA loops. In addition, the CD model was developed by taking into account the trapping effects of 1D migrating SIA loops by ether V-C complexes or solute atoms, and preliminary calculations were performed. Results of calculation and those of irradiation experiments for 
-iron and austenitic stainless steel were compared. The difference and underlying mechanism of microstructural evolution between -iron and austenitic stainless steel is discussed.