2004 Fiscal Year Final Research Report Summary
Improvement in radiation resistance in refractory transition metals such as tungsten by radiation induced ductilization
| Project/Area Number |
13308022
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Tohoku University |
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Principal Investigator |
KURISHITA Hiroaki Tohoku University, IMR, International research center for nuclear materials science, Associate Professor, 金属材料研究所, 助教授 (50112298)
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| Co-Investigator(Kenkyū-buntansha) |
HATAKAYAMA Masahiko Tohoku University, IMR, International research center for nuclear materials science, Research associate, 金属材料研究所, 助手 (30375109)
HIRAOKA Yutaka Okayama University of Science, Department of applied physics, Professor, 理学部, 教授 (70228774)
TAKIDA Tomohiro Allied Material Corp., Electronic materials dept., Assistant Manager, 主査
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| Project Period (FY) |
2001 – 2004
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| Keywords | radiation-induced precipitation / radiation-induced martensitic transformation / ultra-fine grain / dispersoids / high energetic perticle irradiation / radiation damage / radiation embrittlement / radiation hardening |
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| Research Abstract |
Methodologies for significant improvement in resistance to radiation embrittlement in refractory transition metals such as tungsten involve the applications of radiation-induced intergranular precipitation, radiation-induced martensitic transformation and introduction of a very high density of sinks for irradiation induced point defects. Therefore, pre-irradiation microstructural states and irradiation conditions for each of the three aspects to effectively occur have been examined. It is shown that radiation-induced intergranular precipitation can occur in microstructures comprising fine grains and fine grain-boundary dispersoids with a lower dislocation density under a temperature-cycle irradiation condition. Radiation-induced martensitic transformation can occur in microstructures of fine grains with a high purity matrix under irradiation at lower irradiation temperatures with higher doses. The introduction of a very high density of sinks can include the above two aspects of the microstructural conditions providing that the purity is high in the fine grains with a lower dislocation density, and can provide beneficial effects over wide irradiation conditions. This situation was, however, quite difficult especially for tungsten with maintaining other properties including sufficient relative density and toughness before irradiation. In this study, the desired microstructure has been successfully introduced for W-(0.3-0.7)%TiC by advanced powder metallurgical methods : e.g., the grain size is as low as 50-100nm with the relative density of approximately 99% and the fracture strength of 2GPa. It has been demonstrated so far that W-(0.3-0.7)%TiC exhibits very high resistance to irradiation by fast neutrons and high energy ions such as He and N_2. The results show that the material is very promising for the use as divertors and structural materials exposed to irradiation environments.
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Research Products
(22 results)
