| Co-Investigator(Kenkyū-buntansha) |
OKA Tohru Hitachi Metals Ltd. Research and Level. Division Engineer, 開発本部, 主担技師
SUGIMOTO Satoshi Tohoku Univ. Faculty of Eng. Associate Professor, 工学部, 助教授 (10171175)
TANAKA Terumi Tohoku Univ. Faculty of Eng. Research Instructor, 工学部, 助手 (70005289)
OKADA Masuo Tohoku Univ. Faculty of Eng. Associate Professor, 工学部, 助教授 (80133049)
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| Budget Amount *help |
¥9,700,000 (Direct Cost: ¥9,700,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1989: ¥7,900,000 (Direct Cost: ¥7,900,000)
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| Research Abstract |
The purpose of the present investigation is to develop the low cost R-Fe-B permanent magnets in selectiing the low cost R elements among available various rare-earth elements. Good candidate rare-earth elements for this purpose is the family of so called "didymium" which is the mixture of Nd, Pr, and Ce. The didymium is then abundant and inexpensive. One might say that a mischmetal will be also abundant and inexpensive, and is the good candidate for low cost R-Fe-B magnets. But it is reported that La, which is the main constituent of mishmetal, does not form the R Fe B compounds. Thus, didymium will be better candidate.
The best magnetic properties obtained in present studies are Br=13.2kG, Hc=10.2kOe, and (BH)max=320kJ/m(40MGOe) with Fe33.5%-(5%Ce-didymium)-1%B alloy. Temperature dependence of iHc of
5%Ce-didymium and didymium alloys arealmost same as that of the Fe-33.5% Nd-1%B alloy.
Ce play an important role in densification of the alloy as sintering aid, and in lowering the melting point of (NdPr) Fe B compounds and making it possible to sinter at relatively low temperatures of 104'C. Economically, 40%Ce-didymium alloys are most inexpensive, and give the energy products of 27MGOe, but have the high temperature coefficient. The iHc of 40%Ce- didymium alloy decrease rapidly, by about 65% of iHc of the room temperature, at 100'C. Alternatively, 5%Ce-didymium-Fe-B sin ter-ed magnets with (BH)max=320kJ/m, are most promising among the present studied low cost alloys.
Didymium-Fe-B magnet alloys are also available magnetic powders for bonded magnets.
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