| 摘要 |
PURPOSE:To improve maximum energy product by specially heat treating R-Co- Fe-Cu-Zr-O series material having a specific composition. CONSTITUTION:A material having a composition containing 22-28wt.% of R (where R is one or more types of rare earth elements containing yttrium), 5.5-17.5wt.% of Fe, 1-5wt.% of Cu. 0.5-6wt.% of Zr, 0.03-0.8wt.% of 0 and the residue of substantially 0 in such a manner that the weight ratio of the Fe to the Co is 0.1<=Fe/Co<=0.28 is employed. The material having such a composition is sintered at 1150-1250 deg.C, and solubilized at a temperature lower than the sintering temperature of 1100-1230 deg.C. Then, it is isothermally treated as first stage ageing at 400-900 deg.C for 1 hour or more, then isothermally treated as second stage ageing at a temperature higher than that at the first stage ageing of 700-1000 deg.C, and then cooled continuously at the cooling speed of 0.1-10 deg.C/min to 300-600 deg.C. Thus, a permanent magnet having high maximum energy product (BH)max can be obtained. |
