| Project/Area Number |
07555479
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Physical properties of metals
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
OKI Kensuke KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Professor, 大学院・総合理工学研究科, 教授 (70037860)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAYAMA Ryoji Mitsubishi Materials Corporation, Central Research Institute, Reseracher, 総合研究所, 研究員
HATA Satoshi KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院・総合理工学研究科, 助手 (60264107)
ITAKURA Masaru KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Res, 大学院・総合理工学研究科, 助手 (20203078)
KUWANO Noriyuki KYUSHU UNIVERSITY,Interdisciplinary Graduate School of Engineering Sciences, Ass, 大学院・総合理工学研究科, 助教授 (50038022)
中山 亮次 (株)三菱マテリアル, 総合研究所, 研究員
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Keywords | HDDR process / neodymium iron boride / anisotropic magnet powder / electron microscopy / microstructure / crystallographic orientation / EDX analysis / EDX分析 |
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| Research Abstract |
The changes in microstructure of Nd-Fe-B and Nd-Fe-Co-B-Zr alloy powders during the hydrogenation-decomposition-desorption-recombination (HDDR) process have been investigated by X-ray diffraction measurements and transmission electron microscope (TEM) observations, in order to clarify the formation of submicron grains of Nd_2Fe_<14>B and the appearance of the magnetic anisotropy in the HDDR powder. It was found that the microstructural changes in the HDDR process start with the formation of cellular and spherical NdH_2 embedded in alpha-Fe matrices. The hydrogenation-decomposition (HD) reaction in the Nd-Fe-Co-B-Zr alloy progresses slower than the one in Nd-Fe-B ternary system. There is no specific crystallographic orientation relationship between the original Nd_2Fe_<14>B and the decomposed phases ; NdH_2 and alpha-Fe. A large amount of boron is contained in the NdH_2 grain in the early stage of the HD process. As the HD process advances, the NdH_2 grain spews out the boron and consequently Fe_2B grains appear at relatively latter stage. The magnetic anisotropy decreases with the formation of the Fe_2B grains in the decomposed texture. In the desorption-recombination (DR) stage, the rim-like Nd_2Fe_<14>B phase is formed by the recombination at the boundaries between the NdH_2 particles and the alpha-Fe matrix. The rim phase is composed of some fine Nd_2Fe_<14>B grains whose crystallographic orientations are strongly correlated with one another. After further hydrogen desorption, the rim phase grows up to form the recombined Nd_2Fe_<14>B fine grains with a strongly correlated c-aixs. The grain size of the recombined Nd_2Fe_<14>B crystal is related to the size and the number density of the NdH_2 particles. It is thus expected to obtain superfine Nd_2Fe_<14>B crystals if the NdH_2 particle before the HD stage can be controlled smaller in size and dispersed more density in the alpha-Fe inatrix.
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