1997 Fiscal Year Final Research Report Summary
High-Temperature Deformation and Diffusional Relaxation of Particle-Dispersion Hardened Alloys
| Project/Area Number |
07455278
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 |
KATO Masaharu Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, Professor, 大学院・総合理工学研究科, 教授 (50161120)
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| Co-Investigator(Kenkyū-buntansha) |
ONAKA Susumu Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and, 大学院・総合理工学研究科, 助教授 (40194576)
FUJII Toshiyuki Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and, 大学院・総合理工学研究科, 助手 (40251665)
KAJIHARA Masanori Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and, 大学院・総合理工学研究科, 助教授 (10161035)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Dispersion-hardened alloys / High-temperature deformation / Diffusional relaxation / Orowan mechanism / Creep / Elasticity |
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| Research Abstract |
The main purpose of this research is to understand the role of diffusional relaxation on high-temperature deformation of dispersion-hardened alloys. High-temperature tensile tests were conducted using Cu-SiO_2, Cu-GeO_2 and Cu-Fe alloy single crystals and bicrystals and various stress-strain curves were obtained. In addition, intergranular brittle fracture was found to be very sensitive to the nature of grain boundaries. To quantitatively discuss these experimental results, it was necessary to obtain information on the shape change of dispersed particles that occurs during the deformation. Misorientation-dependent grain-boundary energy must also be characterized. Therefore, basic data on these quantities were also obtained.
As theoretical studies, diffusional relaxation around dispersed particles was analyzed by combining mechanics, thermodynamics and kinetics and the rate equations for the relaxation process could be obtained sucessfully. Furthermore, stable shape of dispersed particles and precipitates under a given set of conditions was quantitatively analyzed using micromechanics.
In comparison with the high-temperature deformation tests, low-cycle fatigue of Cu-Fe alloy single crystals were performed to reveal the effect of dispersed particles on the development of stable dislocation structure. The similarities and differences in the dislocation structure between high-temperature deformation and cyclic deformation were found very clearly.
It is true that this research project has been successfully completed in a sense that it has greatly improved our understanding. What is more important, however, is that this project resulted in the discovery of various new research areas that are essential to understand the high-temperature deformation of dispersion-hardened alloys.
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