PURPOSE: To obtain a hot-worked magnet in which crystal particles are distributed uniformly and whose energy product is high by a method wherein, at an R-T-B-based magnetically anisotropic magnet, the aspect ratio of the crystal particles is at a specific value or higher and the crystal particle size at an end part is equal to or lower than the crystal particle size in the central part.
CONSTITUTION: At an R-T-B-based magnetically anisotropic magnet whose main components are a transition metal (T), rare-earth elements (R) including Y and boron (B), the aspect ratio of crystal particles is set at 2 or higher and the crystal particle size at an end part is equal to or lower than the crystal particle size in the central part. A molten metal whose main components are T, R and B as mentioned above is quenched and solidified; slices are obtained and are broken into pieces ; magnetic powders are formed and pressed densely; a molded body is formed. When the molded body is plastic-worked in a hot manner, its end part is cooled forcibly. For example, a hot press is used so that an upper punch and a lower punch 2, 6 as well as a constrained part 3 at the side face can be heated independently; the temperature at the upper and lower punches 2, 6 at an installation working operation is set at 740°C and the temperature at the constrained part 3 is set at 400°C. Thereby, the size of the crystal particles in the central part and that at the end part of a magnet become uniform.
IWASAKI KATSUNORI
SEKIYAMA MINORU
