HDDR各向异性NdFeB矫顽力机理的研究

研究了HDDR各向异性NdFeB永磁材料的矫顽力机理。通过对材料磁化过程的研究以及对其显微组织结构的观察分析，发现其矫顽力机制起源于畴壁挣脱主相Nd2Fe14B晶粒边界以及晶粒团边界富钕相的钉扎机制，其中富钕相对材料畴壁的钉扎是决定其矫顽力的关键因素。通过理论计算，其结果与材料实际的矫顽力十分接近。此外，还进行了验证性实验并提出了改善材料矫顽力的途径。

Coercivity of HDDR-processed Anisotropic Nd_2Fe_(14)B-based Magnets

The coercivity mechanism of HDDR anisotropic Nd Fe B magnet is investigated. The measurements of magnetization curve and different susceptibilities as well as the observations of microstructure are performed. It is concluded that the magnetic hardening of the magnet is due to the pinning of domain walls at grain boundaries and the Nd rich boundary phase that distributes homogeneously around some colonies composed of fine Nd2Fe14B grains. The coercive field is mainly determined by the pinning of domain walls by the Nd rich boundary phase. The conclusions mentioned above are in good agreement with the theoretical calculation of the intrinsic coercivity of the magnet. Furthermore, experimental verification is carried out and the processes for improving the coercivity of the magnets are proposed.