| Project/Area Number |
14550655
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Kyushu University |
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Principal Investigator |
KURAMOTO Ejichi Kyushu University, Research Institute for Applied Mechanics, Professor, 応用力学研究所, 教授 (30013519)
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| Co-Investigator(Kenkyū-buntansha) |
OHSAWA Kazuhito Kyushu University, Research Institute for Applied Mechanics, Research Associate, 応用力学研究所, 助手 (90253541)
ABE Hironobu Kyushu University, Research Institute for Applied Mechanics, Research Associate, 応用力学研究所, 助手 (90038555)
TSUKUDA Nonoru Kyushu University, Research Institute for Applied Mechanics, Associate Professor, 応用力学研究所, 助教授 (90038563)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | Pressure Vessel Steel / Irradiation Embrittlement / Cu Precipitation in Fe / Positron Annihilation Measurement / Coincidence Doppler Measurement / Electrical Resistivity Measurement / Cu Migration due to SIA / 鉄中の銅析出過程 / 軽水炉圧力容器の脆化 / 照射欠陥 / 塑性変形 |
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| Research Abstract |
It has been clarified that the irradiation embrittlement plays a main role in the determination of the lifetime of the neutron reactor, and the basic process which causes the irradiation embrittlement is the irradiation enhanced Cu precipitation in Fe matrix. In the present study the atomistic feature of this process has been made clear by using the positron annihilation technique and electrical resistivity measurement which were applied for model Fe-Cu alloys irradiated by electrons at low temperature and also deformed at room temperatue. Low temperature irradiation induced vacancies and interstitial atoms into the model alloys and during the isochronal annealing process Cu atoms distributed randomly in the matrix started to form micro-precipitates by the aid of irradiation induced defects. Positrons are trapped not only vacancy type defects but also Cu precipitates because of its high positron affinity. The coincidence Doppler broadening measurement was made for low temperature irradiated or deformed Fe-Cu alloys and from the isochronal annealing measurement, the so-called W-S plot was obtained. This result clearly shows that positrons are trapped and annihilated at Cu-precipitates even at low temperature below stage III (220K). This suggests that self-interstitial atoms contribute to the formation of Cu precipitates. At higher temperatures vacancies also contribute to the formation of Cu precipitates. This new contribution from interstitial atoms is confirmed from the electrical resistivity measurement for the Fe-Cu model alloys irradiated at low temperatures. It is reasonably considered that Cu atoms migrate by the aid of self-interstitial atoms through the so-called mixed dumbbell mechanism. The recent calculation of the atomic size of Cu in Fe matrix shows that Cu is almost the same or slightly larger than Fe, which does not contradict to the mixed dumbbell mechanism.
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