| 摘要 |
<p>A method of manufacturing an Nd-Fe-B microcrystalline permanent magnet which contains a low concentration of rare-earth elements, in which a soft magnetic phase and a hard magnetic phase are intermixed, which has, after cast, an inherent coercive force iHc of not less than 2.5 kOe and a residual flux density Br of not less than 9 kG, which has a cost-performance compared to that of a hard ferrite magnet, and which has a microcrystalline structure having a thickness of 70 νm - 500 νm and contributing to the size and thickness reduction of a magnetic circuit. The melt of an alloy with a specific composition is cast onto a rotating cooling roll in a low-pressure inert gas atmosphere with a pressure not higher than 30 kPa, and a microcrystalline permanent magnet alloy having a microcrystalline structure of 10 nm - 50 nm is directly manufactured from the alloy melt. By employing an alloy melt to which specific elements are added in this manufacturing process, a microcrystalline permanent magnet alloy such that the inherent coercive force iHc can be improved to be not less than 2.5 kOe, an optimum roll circumferential velocity range with which the hard magnetic characteristics can be exhibited can be widened in comparison with the range of the manufacturing conditions of Nd-Fe-B ternary magnet, and the thickness is 70 νm - 500νm can be obtained.</p> |
