| Project/Area Number |
04044126
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Hiroshima University |
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Principal Investigator |
SHIMOMURA Yoshiharu Faculty of Engineering, Hiroshima University, 工学部, 教授 (40033831)
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| Co-Investigator(Kenkyū-buntansha) |
ALFREDO Caro スイス連邦ポール, シェラー(PSI)国立研究所, 高等研究員
TOMAS Diaz d 米国ローレンス, リバモア国立研究所・凝縮固体及び分析科学部門, 高等物理研究員
MICHAEL.W.GU 米国ローレンス, リバモア国立研究所・凝縮固体及び分析科学部門, 高等物理主任研究員
MUKOUDA Ichiro Faculty of Engineering, Hiroshima University, 工学部, 助手 (70209980)
MORIYA Takeshi Faculty of Engineering, Nagoya University, 工学部, 助教授 (40029525)
FUKUSHIMA Hiroshi Faculty of Engineering, Hiroshima University, 工学部, 講師 (70156769)
KIRITANI Michio Collage of Engineering, Nagoya University, 工学部, 教授 (70033826)
CARO Alfredo Paul Sherrer Institute, Switzland
TOMAS diaz de la rubia Lawrence Livermore National Laboratory
GUINAN Michael W. Lawrence Livermore National Laboratory
R.E.STOLLER ストーラー 米国オークリッヂ国立研究所, 金属・セラミックス部門・主任研究員, 上級研究
T.D.DE la Ru 米国ローレンス, リバモア国立研究所・凝縮固体及び分析科学部門, 上級研究員
M.W.GUINAN ガイナン 米国ローレンス, リバモア国立研究所・凝縮固体及び分析科学部門・主任研究員, 上級研究
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 1993: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1992: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Radiation damages / EAM many body potential / Atomistics of void nucleation / by neutron irradiation / Molecular dynamics / Hydrogen atoms / Super-computer / Dynamical damaging processes / Helium atoms / EAMポテンャン / ボイド形成機構 / 格子間原子集合体 / 動的挙動ムービー化 / カスケード・オーバーラップ |
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| Research Abstract |
In materials which are irradiated with neutrons, primary knock-on atoms of high energy are generated. Subsequently displacement damage cascades are formed. Damage structure in materials evolves with cascade damage overlapping, structural relaxation due to thermal vibration at high temperature, formation of voids and bubbles due to gas atoms generated by transmutation nuclear reactions and precipitates formation in alloys. In the present work of this year, atomistics of void formation are studied which are the most important and serious defect in breeder and fusion reactors.
1.Utilizing eam many body potential of pure copper and pure nickel, atomistics of void formation was examined by molecular dynamics computer-simulation. These two materials have low stacking fault energy for pure copper and high stacking fault energy for pure nickel. These reflect the formation of relaxed (collapsed) stacking fault tetrahydra in copper and dislocation loops in nickel. When hydrogen atoms are trapped
… More
in small vacancy clusters, hydrogen atoms move around surface of voids and prevent the collapsing of vacancy clusters. This leads to the formation of voids in irradiated metals. Helium atoms could not move so fast in void embryo. Therefore, helium atoms are questionable to be effective gas atom on the formation of voids.
2. To test reliability of the results of computer-simulation, copper and nickel were irradiated in fusion reactor to heavy high fluence at FFTF breeder reactor in Pacific Northwest Laboratory in the united state. Specimens are two kinds. One is as-received from the manufacture. Another is out-gassed by melting in ultra-high vacuum in order to remove the residual gas dissolved in as-received specimens. Only one capsule was success-fully irradiated. We could observe the remarkable difference of void number density in irradiated specimens. Out-gassed specimen shows low density of voids, while we observed high density of void in as-received specimens. Many other capsules show either sodium leakage or gas-leakage. In these cases, difference of void density could not be observed.
3. It is widely believed that helium atoms contribute more seriously on the formation of voids. We examined its by computer MD simulations. Less
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