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Journal Articles

${it In situ}$ WB-STEM observation of dislocation loop behavior in reactor pressure vessel steel during post-irradiation annealing

Du, Y.*; Yoshida, Kenta*; Shimada, Yusuke*; Toyama, Takeshi*; Inoue, Koji*; Arakawa, Kazuto*; Suzudo, Tomoaki; Milan, K. J.*; Gerard, R.*; Onuki, Somei*; et al.

Materialia, 12, p.100778_1 - 100778_10, 2020/08

In order to ensure the integrity of the reactor pressure vessel in the long term, it is necessary to understand the effects of irradiation on the materials. In this study, irradiation-induced dislocation loops were observed in neutron-irradiated reactor pressure vessel specimens during annealing using our newly developed WB-STEM. It was confirmed that the proportion of $$<100>$$ loops increased with increasing annealing temperature. We also succeeded in observing the phenomenon that two $$frac{1}{2}$$$$<111>$$ loops collide into a $$<100>$$ loop. Moreover, a phenomenon in which dislocation loops decorate dislocations was also observed, and the mechanism was successfully explained by molecular dynamics simulation.

Journal Articles

Influence of applied load on oxidation in the vicinity of crack tips of stainless steel under high temperature water

Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Hanawa, Satoshi

Zairyo To Kankyo, 68(9), p.240 - 247, 2019/09

In order to study environment assisted cracking mechanism of stainless steel under BWR primary coolant condition, effects of applied load on oxidation in the vicinity of crack tips of CT specimens were evaluated. Loaded CT specimens were immersed in an aqueous condition at 290$$^{circ}$$C as a simulated BWR coolant condition, and microstructural observation on oxide near the tips of pre-cracks was carried out. Oxide inner layers, which consisted of fine grain magnetite containing Fe and Cr were formed, and oxide outer layers consisting of large grains of Fe$$_{3}$$O$$_{4}$$ were observed to cover the inner layers. FEM analysis of stress and strain in the loaded CT specimen suggests that both of dislocations due to localized plastic deformation and elastic strain could play important roles to accelerate inner oxide formation in the vicinity of the crack tip of the specimens.

Journal Articles

Analyzing the cross slip motion of screw dislocations at finite temperatures in body-centered-cubic metals; Molecular statics and dynamics studies

Suzudo, Tomoaki; Onitsuka, Takashi*; Fukumoto, Kenichi*

Modelling and Simulation in Materials Science and Engineering, 27(6), p.064001_1 - 064001_15, 2019/08

 Times Cited Count:3 Percentile:33.67(Materials Science, Multidisciplinary)

Plasticity of body-centered-cubic (BCC) metals at low temperatures is determined by screw dislocation kinetics. Because the core of screw dislocation in these metals has non-planar structure, its motion is complex and unpredictable. For example, although density functional theory (DFT) predicts slip on a { 110 } plane, the actual slip plane at elevated temperatures departs from the prediction, its mechanism having been a mystery for decades. Here we conduct a series of molecular dynamics simulations to track the screw dislocation motion and successfully reproduced the transition of the slip plane. We then devised an algorithm to scrutinize the activation of dislocation jump over the Peierls barrier and discovered the possible origin of this unexpected phenomenon, i.e., a large fluctuation leads to the kink-pair nucleation for the cross-slip jump without transition of dislocation core structure.

Journal Articles

Unusual plastic deformation behavior in lath martensitic steel containing high dislocation density

Harjo, S.; Kawasaki, Takuro; Tomota, Yo*; Gong, W.

Materials Science Forum, 905, p.46 - 51, 2017/08

Journal Articles

Recent progress of line-profile analyses for neutron or X-ray diffraction

Tomota, Yo*; Sato, Shigeo*; Harjo, S.

Tetsu To Hagane, 103(2), p.73 - 85, 2017/01

 Times Cited Count:7 Percentile:39.71(Metallurgy & Metallurgical Engineering)

Journal Articles

Dislocation characteristics in lath martensitic steel by neutron diffraction

Harjo, S.; Kawasaki, Takuro; Gong, W.; Aizawa, Kazuya

Journal of Physics; Conference Series, 746(1), p.012046_1 - 012046_7, 2016/10


 Times Cited Count:3 Percentile:13.22

Journal Articles

Mechanical property change in the region of very high-cycle fatigue

Xiong, Z.; Naoe, Takashi; Wan, T.; Futakawa, Masatoshi; Maekawa, Katsuhiro*

Procedia Engineering, 101, p.552 - 560, 2015/03


 Times Cited Count:1 Percentile:29.13

Very high-cycle fatigue behaviour of SUS316L, which is used as the structural material of the spallation neutron sources, was investigated through the ultrasonic fatigue test with the strain rate of 10$$^2$$ s$$^{-1}$$. Cross-sectional hardness distributions of the fatigue-failed specimens for solution annealed (SA) and cold worked (CW) 316L were measured to understand the cyclic hardening or softening. In addition, the tensile tests of the fatigue-failed specimens were performed at room temperature. Furthermore, the nonlinear ultrasonic system was used for evaluating the dislocation density variation. The results showed the cyclic hardening in the region of very high-cycle fatigue in the case of SA. In contrast, in the case of 10%CW, cyclic softening occurred when the number of cycles below 10$$^6$$ and followed by cyclic hardening. In the case of 20%CW, cyclic softening was observed when the number of cycles below 10$$^7$$, while cyclic hardening occurred subsequently.

Journal Articles

X-ray line profile study on shot/laser-peened stainless steel

Kumagai, Masayoshi*; Akita, Koichi; Imafuku, Muneyuki*; Oya, Shinichi*

Advanced Materials Research, 996, p.39 - 44, 2014/08

 Times Cited Count:3 Percentile:9.4

The microstructural features of shot and laser peened austenitic stainless steels were studied using line profile analysis with X-rays. Although both specimens had similar residual stress profiles toward the depth direction, the microstructural features were different not only on the original surfaces of the specimens but also to several micrometers in depth. The dislocation densities of the SP specimen were greater than that of the LP specimen. And the crystallite sizes of the SP specimen were smaller than that of the LP specimen.

Journal Articles

Swelling of cold-worked austenitic stainless steels irradiated in HFIR under spectrally tailored conditions

Wakai, Eiichi; Hashimoto, Naoyuki*; Robertson, J. P.*; Sawai, Tomotsugu; Hishinuma, Akimichi

Journal of Nuclear Materials, 307-311(Part.1), p.352 - 356, 2002/12

 Times Cited Count:10 Percentile:41.76

no abstracts in English

Journal Articles

Effect of solute atoms on swelling in Ni alloys and pure Ni under He$$^{+}$$ ion irradiation

Wakai, Eiichi; Ezawa, Tadashi*; Imamura, Junko*; Takenaka, Tsuyoshi*; Tanabe, Tetsuo*; Oshima, Ryuichiro*

Journal of Nuclear Materials, 307-311(Part.1), p.367 - 373, 2002/12

 Times Cited Count:17 Percentile:27.16

no abstracts in English

Journal Articles

Magnetic and Fermi surface properties of UPtGa$$_5$$

Tokiwa, Yoshifumi; Ikeda, Shugo*; Haga, Yoshinori; Okubo, Tomoyuki*; Iizuka, Tomoya*; Sugiyama, Kiyohiro*; Nakamura, Akio; Onuki, Yoshichika

Journal of the Physical Society of Japan, 71(3), p.845 - 851, 2002/03

 Times Cited Count:40 Percentile:17.24(Physics, Multidisciplinary)

We succeeded in growing a high-quality single crystal of an antiferromagnet UPtGa$$_5$$ by the self-flux method, and measured the magnetic susceptibility, electrical resistivity, specific heat and de Haas-van Alphen (dHvA) oscillation. We found an antiferromagnetic transition at 26K from the magnetic susceptibility and electrical resistivity measurements. Six dHvA branches were observed, ranging from 1.14$$times$$10$$^7$$ to 1.13$$times$$10$$^8$$ Oe. Fermi surfaces consist of two nearly cylindrical and two spherical Fermi surfaces. The cyclotron mass is large, ranging from 10 to 24 $$m_{rm 0}$$, which is consistent with the electronic specific heat coefficient $$gamma$$ = 57 mJ/K$$^2cdot$$mol.

Journal Articles

Microstructural evolution of Fe-Cr-W model alloys during Fe$$^{+}$$ ion irradiation

Wakai, Eiichi; Hishinuma, Akimichi; Abe, Hiroaki; Takaki, Seiichi*; Abiko, Kenji*

Materials Transactions, JIM, 41(9), p.1176 - 1179, 2000/09

no abstracts in English

JAEA Reports


*; *; *; *; Hasegawa, Makoto;

JNC-TY9400 2000-007, 50 Pages, 2000/03


no abstracts in English

Journal Articles

Hydrogen production effect on microstructure of HFIR; Irradiated low activation F82H steel using $$^{54}$$Fe isotope

Wakai, Eiichi; Hashimoto, N.*; Shiba, Kiyoyuki; Miwa, Yukio; J.P.Robertson*; R.L.Klueh*

Fusion Materials, 313(25), p.151 - 160, 1999/04

no abstracts in English

Journal Articles

Effect of triple beam irradiation on microstructural evolution in austenitic stainless steel

Hamada, Shozo; Y.C.Zhang*; Miwa, Yukio; Yamaki, Daiju

Radiation Physics and Chemistry, 50(6), p.555 - 559, 1997/00

 Times Cited Count:6 Percentile:49.91

no abstracts in English

Journal Articles

Effects of purity and Cr concentration on microstructural evolution in Fe-Cr alloys during electron irradiation

Wakai, Eiichi; Hishinuma, Akimichi; Kato, Yasushi*; *; *

Nihon Kinzoku Gakkai Koen Gaiyo, 1994 Shuki (Dai-115-Kai) Taikai, 0, p.488 - 494, 1994/00

no abstracts in English

Journal Articles

Evolution of structural damage in aluminum alloys irradiated with helium ions

*; Furuno, Shigemi; Hojo, Kiichi; Ono, K.*; *; *; Kino, Takao*

Journal of Nuclear Materials, 191-194, p.1214 - 1218, 1992/00

 Times Cited Count:3 Percentile:63.51

no abstracts in English

Journal Articles

Radiation-induced segregation in FFTF-irradiated austenitic stainless steels

E.A.Kenik*; Hojo, Kiichi

Journal of Nuclear Materials, 191-194, p.1331 - 1335, 1992/00

 Times Cited Count:28 Percentile:9.43

no abstracts in English

Journal Articles

Formation of interstitial loops on transmutation products in aluminum

Ono, K.*; *; Furuno, Shigemi; Kino, Takao*; *; Hojo, Kiichi; *; *; *; *

Journal of Nuclear Materials, 191-194, p.1209 - 1213, 1992/00

 Times Cited Count:0 Percentile:100

no abstracts in English

Journal Articles

Microstructural evolution of Ba$$_{2}$$YCu$$_{3}$$O$$_{7}$$ superconductor by electron irradiation in a transmission electron microscope

Shiraishi, Kensuke;

Materials Research Society Symposium Proceedings, Vol.169, p.835 - 838, 1990/00

no abstracts in English

50 (Records 1-20 displayed on this page)