Preparation of composite ultrastrong permanent magnet composed of hard and soft magnetic materials by MA

本研究的目的是用MA法制备软硬磁体组成的超强永磁体，并成功制备了(Sm-Co)+Fe体系。结果表明：在真空中低温退火后的粉末由直径为10 ~ 30 nm的细晶粒组成，具有优异的磁性能。当退火温度提高到1073 K时，大部分Fe被消耗用于2-17相的生长。Fe的消耗和2-17相的生长导致残余和矫顽力的降低。不含铁的粉末剩余物少，最大能积很低。另一方面，铁对粉末的剩余物有增强作用，剩余物随铁浓度的增加而增加。虽然退磁曲线的形状随铁浓度的变化而变化，但高、低铁浓度样品的最大产物均在100 kj/m^3左右。这种优越的磁性能似乎是硬相和软相交换相互作用的结果。在这个实验中得到的标本是磁性各向同性的。并对如何获得磁性各向异性的Sm_2Fe_<17>N_<2x>试样进行了研究。

The purpose of this research is to develop the ultrastrong permanent magnet composed of hard and soft magnets by MA, and we succeeded in (Sm-Co)+Fe system. The results obtained are summarized as follows : The powder annealed at comparatively low temperature in vacuum after MA was composed of fine grains whose size was 10-30 nm in diameter and showed superior magnetic properties. When the annealing temperature was raised to 1073 K, most of Fe was consumed for the growth of 2-17 phase. This consumption of Fe and the growth of 2-17 phase resulted in the decrease of the remanence and coercivity. The powder without Fe showed low remanence and its maximum energy product was very low. On the other hand, remanence enhancement was found in the powder to which Fe was added, and the remanece increased with increasing Fe concentration. Though the shape of demagnetization curve varied with Fe concentration, the maximum product of about 100 kj/m^3 was obtained for both high and low Fe concentration samples. Such superior magnetic properties seemed to be the result of exchange interaction between hard and soft phase. The specimen obtained in this experiment was magnetically isotropic. And it is under investigation how to get the Sm_2Fe_<17>N_<2x> specimen with magnetic anisotropy.