Preparation of the exchange-spring permanent magnet composite ultrastrong permanent magnet with ultrastrong energy products

以SmCo_5为硬磁相，α-Fe粉为复合相的纳米复合磁体的制备及晶化热处理。研究了α-Fe相含量对磁性的影响。机械合金化（SmCo_5）_<1-x>Fe_x粉末由Sm-Co非晶相和α-Fe相组成。经823或873 K热处理后，得到SmCo_5相（1-5相）和α-Fe相的复合材料。另一方面，在923或1073 K晶化后，形成2-17相而不是1-5相。在873 K晶化的（SmCo_5）_<1-x>Fe_x粉末具有细小的晶粒组织，晶粒尺寸为10-20 nm。（SmCo_5）_<1-x>Fe_x粉末的剩磁Mr随Fe含量的增加而显著增加，而矫顽力则呈线性下降。（SmCo_5）_Fe_3粉末的最大能量积最大，为105.8kJ/m3<75><25>。（SmCo_5）_<1-x>Fe_x粉末的退磁曲线在第二象限中没有出现软相的台阶，反冲回线显示出较大的可逆磁化强度，可达60%左右。从这些结果可以看出，在这项研究中，软，硬相之间的交换耦合。

Preparation of nanocomposite magnets composed of SmCo_5 as a hard magnetic phase andα-Fe powders and subsequent heat treatment for crystallization. The amount of the soft α-Fe phase was varied, and the effects of Fe content on the magnetic properties have been investigated. The mechanically alloyed (SmCo_5)_<1-x>Fe_x powders were found to be composed of the Sm-Co amorphous phase and α-Fe phase. The composite of a SmCo_5 phase (1-5 phase) andα-Fe phase obtained by heat treatment at 823 or 873K. On the other hand, after crystallization at 923 or 1073K, the 2-17 phase was formed instead of the 1-5 phase. The (SmCo_5)_<1-x>Fe_x powders crystallized at 873K showed fine microstructures composed of grains 10-20 nm in size. The values of remanence Mr of (SmCo_5)_<1-x>Fe_x powders significantly increased with increasing Fe content, on the other hand, the values of coercivity linearly decreased. The maximum value of maximum energy product, 105.8 kJ/m3, was obtained for the (SmCo_5)_<75>Fe_<25> powder. In the demagnetization curves of the (SmCo_5)_<1-x>Fe_x powders in the second quadrant, any step due to the presence of soft phase was not detected and the recoil loops showed a large reversible magnetization reaching about 60 %. From these results, it is evident that exchange coupling between the soft and hard phase was obtained in this study.