| Project/Area Number |
12450255
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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 |
Physical properties of metals
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| Research Institution | Tohoku University |
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Principal Investigator |
IIJIMA Yoshiaki Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (70005411)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAKI Seiichi Tohoku University, Institute of Materials Research, Research Associate, 金属材料研究所, 助手 (70005966)
ABIKO Kenji Tohoku University, Institute of Materials Research, Associate Professor, 金属材料研究所, 助教授 (80005959)
YAMAZAKI Yoshihiro Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (30292246)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥13,100,000 (Direct Cost: ¥13,100,000)
Fiscal Year 2001: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2000: ¥10,700,000 (Direct Cost: ¥10,700,000)
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| Keywords | high-purity / Fe-Cr alloy / diffusion / volume diffusion / grain-boundary diffusion / W addition / σ phase / carbide / 粒界強化機構 |
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| Research Abstract |
So far, most of experimental studies on self-diffusion in the Fe-Cr binary alloys have been limited in the Fe-rich solid solution range less than 20at%Cr. Recently, Abiko and coworkers have found that the ductility of a Fe-50mass% Cr alloy is remarkably improved by purification. This remarkable improvement of mechanical properties of the high purity Fe-50Cr alloy stimulates us to study the diffusion of the alloy. In the present work, the volume and grain-boundary self-diffusion coefficients in the high purity Fe-50-60 mass% Cr alloys and Fe-50mass%Cr-8mass%W alloys have been determined. The experimental results are summarized as follows:
(1) Linear Arrhenius relations for the volume self-diffusion of both components in the Fe-50mass%Cr alloy have been observed across the transformation temperature of the σ phase, suggesting that there is little σ phase in the alloy and that it gives negligible influence on the volume diffusion.
(2) Downward curved Arrhenius lines for the grain boundary diffusivity sδD_<gh> of both tracers in the Fe-50mass%Cr alloy have been observed. This is attributed to the formation of very thin layer of the (Cr,Fe)_<2.3>C_6 phase at the grain boundary near the surface of the specimens.
(3) Volume diffusion coefficients of Cr and Fe in a high-purity Fe-50mass%Cr-8mass%W alloy in the temperature range from 1023 to 1323 K are smaller than those in a high purity Fe-50mass%Cr alloy.
(4) Grain-boundary diffusivities of Cr and Fe in the high-purity Fe-50mass%Cr-8mass%W alloy are smaller than those in a high-purity Fe-50mass%Cr alloy.
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