2003 Fiscal Year Final Research Report Summary
Strengthening of materials caused by dispersion of doughnut-like second phase
| Project/Area Number |
14550683
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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 |
Structural/Functional materials
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ONAKA Susumu Interdisciplinary Graduate School of Science and Engineering, Department of Materials Science and Engineering, Associate Professor, 大学院・総合理工学研究科, 助教授 (40194576)
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| Co-Investigator(Kenkyū-buntansha) |
FUJII Toshiyuki Interdisciplinary Graduate School of Science and Engineering, Department of Innovative and Engineered Materials, Associate Professor, 大学院・総合理工学研究科, 助教授 (40251665)
KATO Masahaur Interdisciplinary Graduate School of Science and Engineering, Department of Materials Science and Engineering, Professor, 大学院・総合理工学研究科, 教授 (50161120)
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| Project Period (FY) |
2002 – 2003
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| Keywords | elastic strain energy / micromechanics / toroid / material strengthening / precipitates |
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| Research Abstract |
We have made the following studies to understand the change of mechanical properties of materials caused by dispersion of doughnut-like second phase.
Cu-Si alloys are internally oxidized at various of Si atoms with oxygen, film-like SiO_2 precipitates formed on grain boundaries (GBs) is observed. After the reaction of Si atoms with oxygen, film-like SiO_2 precipitates with holes which expose GB of Cu are initially formed. At temperatures used for the internal oxidation, the holes rapidly grow and the morphology of the film-like SiO_2 evolves to a particulate equilibrium shape through formation of two-dimensional SiO_2 network.
Theoretical calculations to understand effects of doughnut-like inclusions on the mechanical properties of materials are made. The averaged Eshelby tensors that relate uniform eigenstrains and average total strains in doughnut-like inclusions are obtained. These are compared with the Eshelby tensors of oblate spheroidal and rod-like inclusions. We show that the averaged Eshelby tensors of the doughnut-like inclusions on a plane are almost the same as the average of the Eshelby tensors of randomly oriented rod-like inclusions on the same plane. This is satisfied for both "thin" doughnut-like inclusions. The strain field caused by uniform and purely dilatational eigenstrains is also discussed for a doughnut-like inclusion. Near the doughnut-like inclusion, there are two points where all components of the strains are null. Using the results results obtained, we have discussed the effects of the doughnut-like inclusions on the mechanical properties of materials.
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