| 摘要 |
PURPOSE:To provide a cast rare earth-iron permanent magnet which does not need grinding, sintering and is inexpensive by casting an alloy which has rare earth element including Y, B, Co and iron, and then heat treating at specific temperature or higher. CONSTITUTION:An alloy which contains 8-25, 2-8 and up to 40atom% of R, B and C, the residue of iron and other unavoidable impurities in production is melted, so cast that the cast macrostructure is a columnar crystal, and a cast ingot is heat treated at 500 deg.C or higher to be magnetically cured. The main phase of the obtained R-Re-B magnet is R2Fe14B. If the R is 8atom% or less, this compound is not formed, and since it become the same cubic structure as alpha-iron, high magnetic property is not obtained. If the R exceeds 25atom%, the magnetic property that nonmagnetic R-rich phase content is not large is remarkably reduced. If the B is less than 2atom%, the alloy becomes rhombic structure in R-Fe alloy, and high coercive force is not obtained. If the B is 8atom% or higher, the coercive force in the cast state cannot be obtained. The Co is a useful element to raise Curie point and to improve temperature characteristic, and up to 40atom% of the Co is proper due to low cost and easy workability. |
