| 摘要 |
PURPOSE:To obtain the rare-earth iron permanent magnet having excellent magnetic characteristics by a method wherein a vacuum sintering is performed in a sintering process at first, and then a sintering is performed in a non- oxidizing gas atmosphere. CONSTITUTION:After the raw powder obtained by pulverzing a rare-earth iron permanent magnet is molded, a two-stage sintering process, namely, the first stage sintering in the pressure-reduced atmosphere of 1 Torr or less and the second stage sintering in the atmosphere of 100 Torr or more wherein non- oxidizing gas is filled up is performed. When a sintering is performed in the atmosphere having the degree of vacuum higher than 1 Torr in the first stage of sintering, the ratio of squareness and the sinterability of the molded material is reduced, and when the non-oxidizing gas pressure is 100 Torr or less in the second stage of sintering, a high sintering density can not be obtained and Br is reduced. According to this invention, the permanent magnet having high Br, IHc and (BH)max can be stably obtained without deterioration of the ratio of squareness and the irregularity of characteristics of the title permanent magnet. |
