2010 Fiscal Year Final Research Report
The study on the strengthening mechanism of ODS steel by the analysis of 3D elemental distribution
| Project/Area Number |
20860091
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| Research Category |
Grant-in-Aid for Young Scientists (Start-up)
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| Allocation Type | Single-year Grants |
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| Research Field |
Structural/Functional materials
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
NOGIWA Kimihiro Japan Atomic Energy Agency, 安全研究センター, 研究員 (80465989)
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| Project Period (FY) |
2009 – 2010
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| Keywords | 酸化物分散強化型鋼 / 3次元アトムプローブ / 超短パルスレーザー |
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| Research Abstract |
Oxide dispersion strengthened (ODS) steels have been considered as attractive candidate materials for fusion reactor blankets and advanced fast reactor fuel cladding tubes, owing to their excellent high-temperature mechanical properties and high swelling resistance. Understanding the quantitative interaction between oxide dispersion state and mechanical properties is important in clarifying the effects of manufacturing conditions. Previous studies have revealed that 9Cr-ODS steel has excellent high-temperature strength as a dual-phase steel consisting of residual-α ferrite and α martensite. Its superior mechanical property results from a high number density of small oxide particles dispersed in the matrix. In this study, we investigate the nanometer-scale microstructure of a ODS steel by atom probe tomography and TEM. It was revealed that the nonstoichiometric clusters have almost the same chemical composition and that their mean size was about 3nm in each phase. On the other hand, the number density of the residual-α phase was about four times higher than that of the α phase. These results are in good agreement with those of mechanical property tests, and demonstrate that one reason for 9Cr-ODS steel having excellent high-temperature strength is the dense distribution of the oxide particles in the residual-α phase.
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