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Journal Articles

International round robin test on Master Curve reference temperature evaluation utilizing Miniature C(T) specimen

Yamamoto, Masato*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Valo, M.*; Lambrecht, M.*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*

Small Specimen Test Techniques; 6th Volume (ASTM STP 1576), p.53 - 69, 2015/05

In order to ensure the robustness of the Master Curve technique, round-robin tests were performed using 0.16 inch-thick Mini-CT specimens by different investigators to see if consistent $$T$$$$_{0}$$ values can be obtained. All the specimens used were machined and pre-cracked by one fabricator from unique Japanese RPV material. Seven institutes participated in this exercise, and obtained valid $$T$$$$_{0}$$ values according to the ASTM E1921 standard. The scatter of $$T$$$$_{0}$$ values obtained was well within the uncertainty range defined in the standard, indicating the robustness of the Mini-CT specimen test technique. Throughout this activity, we could obtain 182 $$K$$$$_{Jc}$$ for a single material. We investigated the statistics of this large database, and found that there is no remarkable difference not only in the $$T$$$$_{0}$$ values but also in the fracture toughness distribution between the Mini-CT specimen and the standard size 1T-C(T) specimen results.

Journal Articles

Effects of irradiation induced Cu clustering on vickers hardness and electrical resistivity of Fe-Cu model alloys

Tobita, Toru; Nakagawa, Sho*; Takeuchi, Tomoaki; Suzuki, Masahide; Ishikawa, Norito; Chimi, Yasuhiro; Saito, Yuichi; Soneda, Naoki*; Nishida, Kenji*; Ishino, Shiori*; et al.

Journal of Nuclear Materials, 452(1-3), p.241 - 247, 2014/09

 Times Cited Count:15 Percentile:76.9(Materials Science, Multidisciplinary)

Three kinds of Fe-based model alloys, Fe-0.018 atomic percent (at.%) Cu, Fe-0.53at.%Cu, and Fe-1.06at.%Cu were irradiated with 2 MeV electrons up to the dose of 2$$times$$10$$^{-5}$$ dpa at 250$$^{circ}$$C. After the irradiation, the increase in Vickers hardness and the decrease in electrical resistivity were observed. The increase in hardness by electron irradiation is proportional to the product of the Cu contents and the square root of the electron dose. The decrease in electrical resistivity is proportional to the product of the square of Cu contents and the electron dose. Cu clustering in the materials with electron irradiation and thermal aging was observed by means of the three dimensional atom probes (3D-AP). The change in Vickers hardness and electrical resistivity is well correlated with the volume fraction of Cu clusters.

Journal Articles

A Round robin propgram of master curve evaluation using miniature C(T) specimens, 3; Comparison of $$T_{0}$$ under various selections of temperature conditions

Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Mabuchi, Yasuhiro*; Viehrig, H.-W.*; Miura, Naoki*; Soneda, Naoki*

Proceedings of 2014 ASME Pressure Vessels and Piping Conference (PVP 2014) (DVD-ROM), 7 Pages, 2014/07

The Master Curve (MC) approach for the fracture toughness reference temperature To is expected to be a powerful tool to ensure the reliability of long-term used RPV steels. In order to get sufficient number of data for the MC approach related to the present surveillance program for RPVs, the use of miniature specimens is important. The test technique for the miniature specimens (Mini-CT) of 4 mm thick had been verified the basic applicability of MC approach by means of Mini-CT for the determination of fracture toughness of typical Japanese RPV steels. A round robin (RR) program was organized to assure the robustness of the technique. As the third step of RR program, blinded tests were carried out. Precise material information was not provided to the participants. From the results obtained, the scatter range in $$T_{0}$$ was within the acceptable scatter range specified in the testing standard. The selection of testing temperature seems to give limited effect like that in larger specimens.

Journal Articles

Hardening induced by energetic electron beam for Cu-Ti alloys

Ueyama, Daichi*; Semboshi, Satoshi*; Saito, Yuichi; Ishikawa, Norito; Nishida, Kenji*; Soneda, Naoki*; Hori, Fuminobu*; Iwase, Akihiro*

Japanese Journal of Applied Physics, 53(5S1), p.05FC04_1 - 05FC04_5, 2014/05

 Times Cited Count:6 Percentile:34.83(Physics, Applied)

In our previous research, it was found that the hardness of Cu-Ti alloy increased by energetic heavy ion irradiation at room temperature. In the conference, we will show the result of electron beam irradiation on the hardness of Cu-Ti alloys. We used CuTi sheets with the dimension of 10 $$times$$ 10 $$times$$ 0.250 mm$$^{3}$$. The specimens were irradiated at 473 K and 523 K with 2 MeV electrons. For comparison, we thermally aged some specimens at the same temperatures as that for the irradiation. The electron fluence of 8.0 $$times$$ 10$$^{17}$$/cm$$^{2}$$ corresponds to the processing time of about 10 h. As a result, the thermal aging for 10 h increases the hardness by 5 or less, which is much smaller than that by the irradiation (about 20). The hardness of the reverse side of irradiated surface is almost the same as that of the irradiated surface. The present result implies that energetic electron irradiation can be a useful tool for controlling the hardness of the "bulk" Cu-Ti alloy.

Journal Articles

A Round robin program of master curve evaluation using miniature C(T) specimens; First round robin test on uniform specimens of reactor pressure vessel materials

Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Chiba, Atsushi*; Hirano, Takashi*; Sugihara, Takuji*; Sugiyama, Masanari*; Miura, Naoki*; et al.

Proceedings of 2012 ASME Pressure Vessels and Piping Conference (PVP 2012) (DVD-ROM), 7 Pages, 2012/07

Master curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data for the MC approach from broken halves of surveillance test specimens for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach of a Japanese RPV steel has been launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out further investigation items to be solved. As the first step of this program, four institutes carried out MC testing and evaluation using common test procedure and specimens. Valid reference temperature T$$_{0}$$ was successfully obtained in each institute. However, the T$$_{0}$$ values showed large differences with maximum of 34$$^{circ}$$C. It was indicated on the reason of difference that there is a strong correlation between the T$$_{0}$$ values and loading rate, which was selected by each institute per test standard.

Journal Articles

Hardness modification of aluminum-alloys by means of energetic ion irradiation and subsequent thermal aging

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Nuclear Instruments and Methods in Physics Research B, 272, p.49 - 52, 2012/02

 Times Cited Count:7 Percentile:52.71(Instruments & Instrumentation)

Journal Articles

Hardening of Al-Cu-Mg alloy by energetic ion irradiation

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Journal of Nuclear Materials, 408(2), p.201 - 204, 2011/01

 Times Cited Count:11 Percentile:66.95(Materials Science, Multidisciplinary)

Journal Articles

Impact of advanced experimental method on nuclear materials R&D; The Progress of technology has brought about a deep understanding !

Kimura, Akihiko*; Nagai, Yasuyoshi*; Fujii, Katsuhiko*; Nishiyama, Yutaka; Soneda, Naoki*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 50(10), p.630 - 633, 2008/10

no abstracts in English

Journal Articles

First-principles molecular dynamics simulation of SiC devices; Generation of amorphous SiO$$_{2}$$/SiC interface

Miyashita, Atsumi; Yoshikawa, Masahito; Kano, Takuma; Onuma, Toshiharu*; Sakai, Takayuki*; Iwasawa, Misako*; Soneda, Naoki*

Annual Report of the Earth Simulator Center April 2004 - March 2005, p.287 - 291, 2005/12

Silicon carbide semiconductor device is expected to be used under a severe environment like the nuclear reactor and the space environment. On the semiconductor device interface, the electric charge state of the defect decides an electric characteristic. To emulate interfacial structure the $$rm SiO_{2}/SiC$$ interface structure is generated and the electronic geometry is decided by the first-principle molecular dynamics simulation with the earth simulator. The amorphous $$rm SiO_{2}/SiC$$ interface structure is made by medium-scale model of about 400 atoms. The heating temperature is 4000K, the heating time is 3.0ps, the speed of rapid cooling is -1000K/ps, and SiC movable layers in the interface are assumed to be 4 layers. In temperature 2200K the $$rm SiO_{2}$$ terminal was opened to make the $$rm SiO_{2}$$ layer more amorphous. The model has almost abrupt interface, however, some defects energy levels were still observed in the band gap. The energy levels are originated from interfacial oxygen. The localized electronic distribution of the dangling bond causes defect energy levels.

Oral presentation

First-principles molecular dynamics simulation of oxide layers for SiC devices

Miyashita, Atsumi; Onuma, Toshiharu*; Sakai, Takayuki*; Iwasawa, Misako*; Yoshikawa, Masahito; Kano, Takuma; Soneda, Naoki*

no journal, , 

no abstracts in English

Oral presentation

First-principles molecular dynamics simulation of oxide layer for radiation-tolerant SiC devices

Miyashita, Atsumi; Onuma, Toshiharu*; Sakai, Takayuki*; Iwasawa, Misako*; Kano, Takuma; Soneda, Naoki*; Yoshikawa, Masahito

no journal, , 

no abstracts in English

11 (Records 1-11 displayed on this page)
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