2001 Fiscal Year Final Research Report Summary
Studies on the generation mechanism of peculia effect of scandium addedin aluminum alloys
| Project/Area Number |
12650688
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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 | Tohoku University |
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Principal Investigator |
FUJIKAWA Shin-itiroh School of Engineering, Tohoku University, Research Associate, 大学院・工学研究科, 助手 (50005344)
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| Co-Investigator(Kenkyū-buntansha) |
IIJIMA Yoshiaki School of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (70005411)
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| Project Period (FY) |
2000 – 2001
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| Keywords | scandium / Al-Sc alloys / impurity diffusion / NMR / aluminum alloys / precipitation / interface energy / resistivity measurement |
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| Research Abstract |
Scandium has the excellent ability to improve various properties of aluminum alloys in solid state and liquid state, but have now not completely clarified. In present work, the precipitation behabior of equilibrium Al_3Sc precipitates and the impurity diffusion of Sc in aluminum were mainly studied. The precipitation kinetics of equilibrium Al_3Sc precipitates in AI-Sc alloys and Al-Mg-Sc alloys was investigated by electrical resistively measurements and nuclear magnetic resonance (NMR). From the kinetical studies the rate constants were determined. The impurity-diffusion coefficients of Sc in aluminum were measured by the self-made radioactive tracer of Sc and serial-sectioning method over the wide temperature range. The results were compared with those of other transition elements in aluminum. Al(fcc) / Al_3Sc interphase boundary energy was estimated by the rate constants and impurity diffusion data of Sc in aluminum. The precipitation and dissolution of Al_3Sc phases in Al-Sc and Al-Mg-Sc alloys was investigated by NMR. This method is found to be very effective for obtaining about the phase diagram's information in the binary Al-Sc and ternary Al-Mg-Sc system. From measurement of complete homogenization temperature for Al_3Sc phases in Al-Sc alloy, the solid solubility line of Sc in aluminum determined by Fujikawa in 1973 is recognized to be reasonable. The solid solubility line of Sc for Al-Mg-Sc system is found to shift to lower concentration side than that for Al-Sc system. Under same aging condition, the precipitation rate of A1_3Sc in Al-Mg-Sc alloys is found to be faster than that in Al-Sc alloys.
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