Thermal Reduction and Diffusion Treatment and Magnetic Properties of Nd-Fe-B Sintered Magnets using Rare Earth Oxyhalides

Abstract

Rare earth oxyhalides, e.g. DyOCl and TbOCl, which are easily termed in the purification process for rare earth raw materials and chemically stable compared to DyCl₃ or TbCl₃, have been reduced by CaH₂ under a heated conditions, and the resultant Dy or Tb metal has been introduced to the inside of Nd-Fe-B magnet pieces. The Dy or Tb metal modified magnets showed the higher coersivity without any reduction of the remanence values than the untreated magnets.