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 oxide 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 having the compsn. constituted of, by atom, 8 to 30% of at least one kind among rear earth elements such as Nd, Pr, La, Ce, Dy, Sm, Tb, Gd and Yb, 2 to 28% B and the balance Fe is mixed with one or more kinds among the oxide powder of rare earth elements such as Y, Ho, Er, Tm, Lu and Eu in the total ratio of 0.0005 to 2.5wt.%. 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 and 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.