| 摘要 |
PURPOSE:To improve coercive force by adding small quantity of B to a permanent magnet material which consists of the rare earth element, CO, Cu and Fe. CONSTITUTION:Permanent magnet alloy is made from 20-35% of R (Y and one or more of rare earth elements), 5-15% of Cu, 3-20% of Fe, 0.002-0.5% of B and the residual part which means substantially CO in weight per cent. In the system which contains R-CO-Cu-Fe, adding ratio of R must be 20% or more to hold excellent (BH)max. On the other hand excess addition makes residual magnetic flux density Br lower, so the maximum shall be 35%. Adding ratio of Cu is 5% or more to hold the excellent coercive force IHc. However excess addition makes Br lower, so a maximum shall be 15%. Adding ratio of Fe mush be 3% or more to hold the excellent Br. However excess addition makes IHc lower sharply, so adding ratio shall be 20% or less. Addition of B in small quantity can improve IHc remarkably. Its effect is remarkable on adding ratio 0.002-0.5%. |
