MANUFACTURE OF RARE EARTHS-B-FE SERIES SINTERED MAGNET HAVING EXCELLENT CORROSION RESISTANCE AND MAGNETIC CHARACTERISTICS

摘要

PURPOSE:To obtain the sintered magnet having excellent corrosion resistance and magnetic characteristics by mixing alloy powder contg. rare earth elements, B and Fe as essential components with the hydride powder of specified elements, forming the mixed powder and thereafter sintering it in a nonoxidizing atmosphere. CONSTITUTION:The powder of a rare earths-B-Fe series alloy constituted of at least one kind among rare earth elements excluding Y such as Nd, Pr or their mixture, 8 to 30atom%, 2 to 28atom% B and the balance Fe is admixed with one or more kinds of hydride powder of elements such as Zr, Ta, Ti, Nb, Hf, V and Y in the total ratio of 0.0005 to 3wt.%. If required, a forming auxiliary such as paraffin is added to the mixed powder, which is subjected to press forming. The formed part is sintered at 900 to 1200 deg.C in vacuum or in the atmosphere of nonoxidizing gas such as inert gas, reducing gas or the like. The product is finally subjected to heat treatment at 400 to 700 deg.C, by which the sintered magnet having excellent corrosion resistance and magnetic characteristics can be manufactured.