| Project/Area Number |
07555208
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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 |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
HOMMA Motofumi Tohoku University, Graduate School of Engineering, Prof., 大学院・工学研究科, 教授 (50005261)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Hajime Tohoku University, Graduate School of Engineering, Res.Assoc., 大学院・工学研究科, 助手 (40250716)
KAGOTANI Toshio Tohoku University, Graduate School of Engineering, Res.Assoc.., 大学院・工学研究科, 助手 (40005343)
SUGIMOTO Satoshi Tohoku University, Graduate School of Engineering, Assoc.Prof., 大学院・工学研究科, 助教授 (10171175)
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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 |
¥12,200,000 (Direct Cost: ¥12,200,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 1995: ¥7,300,000 (Direct Cost: ¥7,300,000)
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| Keywords | magnetizing ability / sintered magnet / Nd2Fe14B / inverse domain / magnetic domain / coercivity / remanence / maximum energy products / 焼結磁石 / Nd_2Fe_<14>B / 残留磁束密度 / 磁化エネルギー / 局所的反磁界 / 着磁 / 永久磁石 / Nd-Fe-B系磁石 / 反磁界 |
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| Research Abstract |
Purpose : Nd-Fe-B sintered magnets exhibit high coercivity, remanence and the maximum energy products. However, high applied field over 1.2 MA/m, was needed to obtain good magnetic properties. Then Nd-Fe-B sintered magnets with good magnetizing ability, which show higher magnetic properties with lower magnetizing field, have been strongly demanded in order to make a small multipole magnets. In this study, the effects of the microstructure (alignment of Nd_2Fe_<14>B particles and the amount of non-magnetic phases) and magnetizing temperature on the magnetizing ability were investigated.
Experimental Procedures : The compositions of studied alloys were Nd_<15>Fe_<77>B_8 and Nd_<14.4>Fe_<79.6>B_<6.0>. These alloy powders were prepared by the conventional powder metallurgy method or the powder mixing method utilizing hydrogen decrepitation. These fine powders were pressed into the compacts in a magnetic field of 0.98MAm^<-1> at a pressure of 100Pa. Magnetic properties were measured by BH looptracer and vibrating sample magnetometer (VSM). The magnetizing ability were evaluated by the ratio of the magnetic properties with every applied field to those after applying pulsed field of 4.0MAm^<-1>. The microstructures were observed using a optical microscope and a scanning electromicroscopy.
Results : The magnetizing ability improved with decreasing the amount of non-magnetic phases and increasing alignment of Nd_2Fe_<14>B particles. The main facter affecting magnetizing ability is the demagnetization field breaking out around the Nd_2Fe_<14>B particles. It is found that magnetizing at high temperature is useful method for increasing magnetizing ability. Because the demagnetization field is closely related to the saturate magnetization of Nd_2Fe_<14>B particles and it decreases with increasing temperature.
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