Iron-based permanent magnets and their fabrication as well as iron-based permanent magnet alloy powders for permanent bonded magnets and iron-based bonded magnets

摘要

With the invention of establishing fabrication methods for cheaply produced (Fe,Co)CrBR-type bonded magnets or (Fe,Co)CrBRM-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 -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 meltquenching of a (Fe,Co)CrBR(Pr,Nd)-type molten alloy or a (Fe,Co)CrBRM (MAl,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 m500 m 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 iHc5 kOe, Br5.5 kG and (BH)max6 MGOe.