*Article* **Design of Glass Fiber-Doped High-Resistivity Hot-Pressed Permanent Magnets for Reducing Eddy Current Loss**

**Yingjian Guo, Minggang Zhu \*, Ziliang Wang, Qisong Sun, Yu Wang and Zhengxiao Li**

Division of Function Materials, Central Iron and Steel Research Institute, Beijing 100081, China; yingjguo@126.com (Y.G.)

**\*** Correspondence: mgzhu@126.com

**Abstract:** The Nd-Fe-B hot-deformation magnet with high resistivity was successfully prepared by hot-pressing and hot-deformation of Nd-Fe-B fast-quenched powder with amorphous glass fiber. After the process optimization, the resistivity of the magnet was increased from 0.383 mΩ·cm to 7.2 mΩ·cm. Therefore, the eddy current loss of magnets can be greatly reduced. The microstructure shows that the granular glass fiber forms a continuous isolation layer during hot deformation. At the same time, the boundary of Nd-Fe-B quick-quenched the flake and glass fiber from the transition layer, which improves the binding of the two, and which can effectively prevent the spalling of the isolation layer. In addition, adding glass fiber improves the orientation of the hot deformation magnet to a certain extent. The novel design concept of insulation materials provides new insights into the development and application of rare earth permanent magnet materials.

**Keywords:** Nd-Fe-B; composite magnet; glass fiber; high resistivity; thermorheological property
