Development of high performance Fe-based magnets utilizing computer analysis and crystallization from amorphous state

通过对Nd-Fe-B基纳米复合磁体的计算机模拟，得到了以下结果。(1)在由60%软磁相和40%Nd_2Fe_ B组成的磁体中，<14>晶粒直径约为20 nm时，获得了较大的最大磁能积。(2)晶粒间交换相互作用强度的波动会使纳米复合磁体的磁性能恶化。(3)通过控制组成磁体的颗粒直径可以制备两种磁体。基于以上结果，我们尝试用Nd-Fe-B非晶合金制备Nd-Fe-B基纳米复合磁体。结果表明：（1）软磁相含量为60%时，磁体具有良好的硬磁性能。(2)为了抑制晶粒间交换作用强度的波动，制备了介于Fe_3 B和Fe_3 B之间的非晶Fe-Si-B<14>磁体。然而，由于软磁相的粒径和量不满足上述条件，因此没有实现硬磁性能的改善。(3)通过控制非晶Nd-Fe-B合金的晶化条件，制备了磁化率高和反冲性能好的两种磁体。

The following results were obtained by computer simulation for Nd-Fe-B-based nanocomposite magnets.(1) Large maximum energy product is obtained in magnets composed of 60% soft magnetic phases and 40% Nd_2Fe_<14>B with about 20nm grain diameter.(2) Fluctuation of the strength of intetgrain exchange interaction deteriorates magnetic properties of nanocomposite magnets.(3) Two kinds of magnets can be prepared by controlling grain diameter consisting of magnets. One of them has good magnetizability and the other has good recoil properties.Based on the above results, we tried to prepare Nd-Fe-B-based nanocomposite magnets from Nd-Fe-B amorphous alloys. The results are :(1) Good hard magnetic properties were obtained in magnets including 60% soft magnetic phases.(2) In order to suppress fluctuation of the strength of intergrain exchange interaction, magnets with amorphous Fe-Si-B phase between Fe_3B and Nd_2Fe_<14>B phases were prepared. However, an improvement in hard magnetic properties was not achieved because the grain diameter and the amount of soft magnetic phases did not satisfy the above-mentioned conditions.(3) Two kinds of magnets, magnets with good magnetizability or those with good recoil properties, were prepared by controlling crystallization condition of amorphous Nd-Fe-B alloys.