1994 Fiscal Year Final Research Report Summary
High Strength Amorphous Alloys with Dispersion of Nano-particles
| Project/Area Number |
04403014
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Tohoku University, Institute for Materials Research |
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Principal Investigator |
MASUMTOTO Tsuyoshi Tohoku Univ., Institute for Materials Research, Professor, 金属材料研究所, 教授 (20005854)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Yoshio Tohoku Univ., Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (30204837)
TSAI An-pang Tohoku Univ., Institute for Materials Research, Assosiate Professeor, 金属材料研究所, 助教授 (90225681)
KIMURA Hisamichi Tohoku Univ., Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (00161571)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Nano-aluminum phase / amorphous phase / aluminum-based alloys / dispersed structure / graim growth |
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| Research Abstract |
In this project, we have developed a novel type of metallic material that is an amorphous matrix with dispersion of nano-crystalline particles. The structure was obtained in several Al-based alloys (Al>87%) by annealing amorphous phase at low temperature (-400K). This materials with precipitation of fcc-Al revealed tensile strength and ductility higher than those for full amorphous phase. Furthermore, in a systematic investigations, it was found that addition of 3at% Cu (or Ag) remarkably improved the mechanical strength. For example, for Al_<87>Ni_7Cu_3Ce_3 alloy, the tensile strength of as-quenched amorphous phase is about 900MPa and it goes up to about 1200MPa after subsequent annealing. Annealing induced increase in tensile strength is caused by the dispersion of fcc-Al particles with size of 5-10nm in the amorphous matrix. The precipitation of fcc-Al was identified to be a growth process of nanocrystalline grains in amorphous phase. The grain process was only observed in the amorphous alloy with Al>87at%, indicating a number nuclei have pre-existed in an Al-enriched area in the original amorphous state. This has been confirmed by small angle X-ray diffraction. In the characterization by atom probe field ion microscopy, Ce seems to be strongly segregated in the fcc-Al/amorphous interface. It was concluded that the segregation of Ce (the atom with large size) supresses the growth of fcc-Al grains and enhances the tensile strength of the material.
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