Abstract: Nanocomposite magnets have become a promising next-generation permanent magnet material due to their potential high magnetic energy product. The implementation of high magnetic performance depends on precise control of the microstructure, including the grain size and distribution of soft and hard magnetic phases, the content of soft magnetic phases, the orientation of hard magnetic phases, the structure and chemical composition, etc. At present, the microstructure of nanocomposite magnets is mainly controlled by adjusting the alloy composition and preparation process. By adding alloying elements, not only can improve the microstructure of nanocomposite permanent magnets, but also can change the intrinsic magnetic parameters of the main phase in the magnet, which is a common method to improve the magnetic performance of the magnet. In this work, the role of alloying elements in microstructure control of RE2Fe14B (RE=Nd, Pr) based nanocomposite permanent magnet materials is summarized and evaluated. The addition of rare earth elements (La, Ce, Pr, Dy, Tb, etc.) to replace Nd atoms alters the intrinsic magnetic parameters of Nd2Fe14B phase. Elements such as Co, Cr, Ni, and Mn can enter the lattice of α-Fe and RE2Fe14B to replace by the point position of Fe, while changing the intrinsic magnetic parameters of the soft and hard magnetic phases, thereby altering the magnetic properties of the magnet. It has been confirmed that elements such as Nb, Ti, and Zr can enter the main phase Nd2Fe14B, but are more enriched at grain boundaries, playing a role in enhancing domain wall pinning and refining grain size. Elements such as Sn and Ga can improve the high-temperature magnetic performance of magnets and enhance their thermal stability. Adjusting the alloy composition through the addition of alloying elements is an effective way to control the microstructure of nanocomposite magnets, but the content of alloying elements should be controlled within a certain range. Excessive addition will deteriorate the magnetic properties of the magnets.

Key words: nanocomposite permanent magnets, exchange coupling interaction, alloying elements, microstructure, intrinsic magnetic parameters

摘要： 纳米复合磁体因其潜在的高磁能积成为颇具发展前途的下一代永磁材料。高磁性能的实现依赖于对微观结构的精确控制，包括软硬磁相的晶粒尺寸及分布、软磁相的含量、硬磁相的取向、界面的结构和化学成分等。目前主要通过调整合金成分和制备工艺来控制纳米复合磁体的微观结构。通过添加合金元素不仅可以改善纳米复合永磁体的微观结构，还可以改变磁体中主相的内禀磁参数，是提高磁体磁性能的常用手段。本工作总结和评述了合金元素在RE2Fe14B (RE=Nd, Pr)基纳米复合永磁材料的微观结构控制方面的作用。稀土元素(La, Ce, Pr, Dy, Tb等)加入取代了Nd原子，改变了Nd2Fe14B相的内禀磁参数；Co, Cr, Ni和Mn等元素可以进入α-Fe和RE2Fe14B晶格并置换Fe的点位，同时改变软、硬磁相的内禀磁参量，从而改变磁体的磁性能。Nb, Ti, Zr等元素被证实可以进入主相Nd2Fe14B内，但更多的是富集在晶界处，起到增强畴壁钉扎和细化晶粒的作用；Sn和Ga等元素可以改善磁体的高温磁性能，提高磁体的热稳定性。通过添加合金元素调控合金成分是控制纳米复合磁体微观结构的有效途径，但合金元素的含量需要控制在一定范围内，过量添加会恶化磁体的磁性能。

关键词: 纳米复合永磁材料, 交换耦合作用, 合金元素, 微观结构, 内禀磁参数