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AssigneeSantoku Metal Industry Co., Ltd.
InventorsKazuhiko Yamamoto, Yuichi Miyake, Chikara Okada
Estimating the term…
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 columnar crystals each having a columnar crystal grain size of 0.1 to 50 .mu.m along a short axis thereof and a columnar 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.degree. C./sec. and not higher than 10,000.degree. C./sec. and a supercooling degree of 50.degree. to 500.degree. C.
A permanent magnet obtained by pulverizing, molding and sintering a starting material comprising 70 to 99.9 vol. % of an alloy ingot, said alloy ingot containing not less than 90% by volume of columnar crystals each having a columnar crystal grain size of 0.1 to 50 .mu.m along a short axis thereof and a columnar crystal grain size of larger than 100 .mu.m and not larger than 300 .mu.m along a long axis thereof, said alloy ingot having been 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.degree. C./sec. and not higher than 10,000.degree. C./sec. and a supercooling degree of 50.degree. to 500.degree. C.
The permanent magnet obtained by pulverizing, molding and sintering a starting material comprising 70 to 100 vol. % of an alloy ingot, said alloy ingot containing not less than 90% by volume of columnar crystals each having a columnar crystal grain size of 0.1 to 50 .mu.m along a short axis thereof and a columnar crystal grain size of larger than 100 .mu.m and not larger than 300 .mu.m along a long axis thereof, said alloy ingot having been 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.degree. C./sec. and not higher than 10,000.degree. C./sec. and a super cooling degree of 50.degree. to 500.degree. C.
Dependencies are inferred from the claim text.