Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
hydride habit planesUdagawa, Yutaka; Yamaguchi, Masatake; Tsuru, Tomohito; Abe, Hiroaki*; Sekimura, Naoto*
Philosophical Magazine, 91(12), p.1665 - 1678, 2011/04
Times Cited Count：15 Percentile：61.31(Materials Science, Multidisciplinary)We have investigated the effects of Sn and Nb on dislocation properties in a Zr lattice in order to elucidate the role of these alloying elements in hydride nucleation processes. According to experimental observations, -hydride habit planes are close to the prismatic plane in pure Zr and close to the basal plane in zircaloy. Dislocation loops are observed around hydride precipitates, implying they play a part in hydride formation. Our ab initio generalized-stacking-fault energy calculations showed remarkable effects of Sn on unstable-stacking energy and stacking-fault energy: these parameters for basal slip were considerably reduced while those for prismatic slip were increased in the presence of Sn. These results suggest selective stabilization and enhancement of dislocation spreading in the basal plane, promoting possible elementary processes of hydride precipitation with basal habit plane, i.e. screw-dislocation spreading and edge-dislocation emission in the basal plane.
Udagawa, Yutaka; Yamaguchi, Masatake; Abe, Hiroaki*; Sekimura, Naoto*; Fuketa, Toyoshi
Acta Materialia, 58(11), p.3927 - 3938, 2010/06
Times Cited Count：96 Percentile：96.4(Materials Science, Multidisciplinary)
TEM observation of growth process of zirconium hydride in zircaloy-4 during hydrogen ion implantationShinohara, Yasunari*; Abe, Hiroaki*; Iwai, Takeo*; Sekimura, Naoto*; Kido, Toshiya*; Yamamoto, Hiroyuki; Taguchi, Tomitsugu
Journal of Nuclear Science and Technology, 46(6), p.564 - 571, 2009/06
Times Cited Count：30 Percentile：87.83(Nuclear Science & Technology) observation during hydrogen ion implantation was performed with a TEM installed in an ion accelerator to investigate the growth process of Zr hydride in Zicaloy-4. To clarify the effect of radiation damage, some samples were irradiated with 4 MeV Ni
ions prior to hydrogen implantation. Growth processes of Zr hydrides accompanying the formation of dislocations were observed. The crystallographic relationship between the Zr matrix and Zr hydrides was identical with that found in previous studies: inter- and intragranular hydrides exhibiting a tendency to grow in the 
11
0
direction. This growth can be attributed to a shear mechanism. In specimens preirradiated with Ni ions, the growth rate of hydrides was suppressed, but the growth direction was not affected by radiation defects. It was also confirmed that the black spots induced by Ni ion irradiation grew during hydrogen ion implantation, suggesting the formation of hydrides at the defects.
Nemoto, Yoshiyuki; Miwa, Yukio; Tsuji, Hirokazu; Tsukada, Takashi; Abe, Hiroaki*; Sekimura, Naoto*
JAERI-Review 2003-033, TIARA Annual Report 2002, p.171 - 173, 2003/11
The aim of this work is to evaluate corrosion behavior of irradiated materials for mechanistic understanding of irradiation assisted stress corrosion cracking (IASCC). Solution annealed high purity Fe-18Cr-12Ni specimens were used in this study. H and He were implanted during irradiation with 12MeV Ni ion at 573K. After corrosion procedure, the specimens were examined with atomic force microscope (AFM) to evaluate corrosion behavior. It was shown that the corroded volume of irradiated area increased with radiation damage. H implantation at lower temperature accelerated corrosion. He implantation suppressed corrosion.
Tsuchiya, Kunihiko; Sekimura, Naoto*; *; G.Kalinin*; ; Kawamura, Hiroshi
Fusion Technology 1998, 2, p.1297 - 1300, 1998/00
no abstracts in English
Ishino, Shiori*; Sekimura, Naoto*; Suzuki, Masahide; *; *; Shibahara, Itaru*
Nihon Genshiryoku Gakkai-Shi, 36(5), p.396 - 404, 1994/00
Times Cited Count：1 Percentile：17.96(Nuclear Science & Technology)no abstracts in English
Udagawa, Yutaka; Yamaguchi, Masatake; Abe, Hiroaki*; Asari, Keisuke*; Shinohara, Yasunari*; Murakami, Kenta*; Nakazono, Yoshihisa*; Mihara, Takeshi*; Sawayama, Yohei*; Sekimura, Naoto*; et al.
no journal, ,
no abstracts in English
Yamaguchi, Masatake; Udagawa, Yutaka; Abe, Hiroaki*; Sekimura, Naoto*
no journal, ,
no abstracts in English
Udagawa, Yutaka; Yamaguchi, Masatake; Abe, Hiroaki*; Sekimura, Naoto*
no journal, ,
no abstracts in English
Yamaguchi, Masatake; Udagawa, Yutaka; Abe, Hiroaki*; Sekimura, Naoto*
no journal, ,
no abstracts in English
Yamaguchi, Masatake; Udagawa, Yutaka; Abe, Hiroaki*; Sekimura, Naoto*
no journal, ,
From first-principles calculations, we investigate solute segregation energy and defect formation energy in hcp Zirconium. We found that segregation energies of some solute elements (Fe, Cr, etc.) are large enough to segregate at Zr grain boundary.
Sekimura, Naoto*; Nakamura, Hideo
no journal, ,
no abstracts in English
