| 摘要 |
A permanent magnet is obtained by pulverizing, molding and sintering a starting material containing an alloy ingot. The alloy ingot contains not less than 90% by volume of prismatic crystals each having a prismatic crystal grain size of 0.1 to 50 mu m along a short axis thereof and a prismatic crystal grain size of larger than 100 mu m and not larger than 300 mu m along a long axis thereof, and is obtained by uniformly solidifying by a single roll method a molten alloy containing 25 to 31% by weight of a rare earth metal, 0.5 to 1.5% by weight of boron and iron under cooling conditions of a cooling rate of higher than 500 DEG C/sec. and not higher than 10,000 DEG C/sec. and a supercooling degree of 50 to 500 DEG C. |
