| 摘要 |
PURPOSE:To stably obtain a permanent magnet having a fixed coercive force by a method wherein, after a magnet alloy has been sintered and age-treated, a cooling treatment is conducted in a specific temperature range at the cooling speed of 10 deg.C/min. or above. CONSTITUTION:An aging treatment is conducted on the sintered alloy consisting of the rare earth element-iron-boron alloy which is used on a rare-earth magnet, and ordinarily the temperature range of 600-700 deg.C is considered desirable as the aging treatment temperature. After the aging treatment has been finished, the sintered alloy is cooled down from the temperature of 570 deg.C or above to at least 470 deg.C or below at the cooling speed of at least 10 deg.C/min. or above. It is necessary that the cooling treatment at the above-mentioned speed is started at least at the aging treatment temperature of 570 deg.C. At this point, if the!starting temperature of said cooling treatment is lower than 570 deg.C, sufficient coercive force is not acquired, and also sufficiently excellent coercive force is not obtained when said cooling speed is not maintained at the temperature lower than 470 deg.C. As a result, the permanent magnet having high coercive force and fixed magnetic characteristics can be obtained in a stable manner. |
