Magnetic properties and magnetization mechanism of anisotropic NdFeB/SmFeN hybrid bonded magnets prepared with different coercivity NdFeB powders

Abstract

Anisotropic NdFeB/SmFeN hybrid bonded magnets were prepared by warm compaction process under an orientation magnetic field of 22 kOe, mixing with anisotropic SmFeN powders in different addition and HDDR–NdFeB powders in different coercivity. With the addition of 20 wt% SmFeN, the density and remanence of hybrid magnets increase from 5.58 g/cm3, 8.4 kGs to 6.02 g/cm3, 9.0 kGs, respectively. And as the addition amount of SmFeN powders varies from 20 wt% to 40 wt%, the maximum energy product changes less than 0.5 MGOe. In addition, the magnetization process and the interactions between two powders were studied. It is found that the magnetization process of anisotropic NdFeB powders shows distinction in different initial states. The addition of SmFeN powders promotes the rotation of NdFeB powders together with applied field, which is beneficial to the degree of alignment of NdFeB powders. Because of the micron-sized long range coupling effect, the coercivity of hybrid magnets decreases slowly with the increase of low coercivity SmFeN. Meanwhile, the magnetization process of hybrid magnets is different from pure magnets, it increases rapidly at low field and then slowly, next leads to rapidity again and achieves the saturation magnetization finally.