| 摘要 |
With the invention of establishing fabrication methods for cheaply produced (Fe,Co)-Cr-B-R-type bonded magnets or (Fe,Co)-Cr-B-R-M-type bonded magnets containing few rare earth elements having a coercive force iHc above 5 kOe and a residual magnetic flux density Br above 5.5 kG matching the cost performance of hard ferrite magnets, we have obtained iron-based permanent magnets consisting of microcrystal clusters where the average crystal size of each component phase is in the range 1 nm ~30 nm and where both a soft magnetic phase consisting of a ferromagnetic alloy whose main components are alpha-Fe and a ferromagnetic alloy having iron, and a hard magnetic phase having a Nd2Fe14B-type crystal structure coexist within the same powder particles, by melt-quenching of a (Fe,Co)-Cr-B-R(Pr,Nd)-type molten alloy or a (Fe,Co)-Cr-B-R-M (M=Al,Si,S,Ni, Cu,Zn,Ga,Ag,Pt,Au,Pb)-type molten alloy of a particular composition containing few rare earth elements, to obtain an essentially amorphous structure or a structure both amorphous and with small amounts of fine crystals, and by applying a crystallization heat treatment under specific conditions. By grinding this iron-based permanent magnet to an average powder particle size of 3 mum~500 mum and combining the resultant iron-based permanent magnet alloy powder with a resin, we can obtain an iron-based bonded magnetic with good thermal and magnetic properties and with the magnetic characteristics iHc>=5 kOe, Br>=5.5 kG and (BH)max>=6 MGOe.
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