高性能NdFeB复合永磁材料微磁结构与矫顽力机制-中国材料进展

文章信息/Info

Title:: Microstructures and Coercivity Mechanism of High Performance Composite NdFeB Permanent Magnets

Author(s):: ZHU Minggang; FANG Yikun; LI Wei; （Department of Functional Material，Central Iron & Steel Research Institute,Beijing 100081,China）

摘要:: 概述了近年来有关高性能NdFeB复合永磁材料矫顽力机制的研究进展, 研究了工艺过程对矫顽力的影响机制和所适应的理论模型，重点探讨了双主相合金技术制备的高性能永磁材料的微结构特征与矫顽力的关系，尝试解释了双主相合金技术制备的高性能永磁材料的矫顽力机制。由传统的单合金或双合金工艺制备磁体的矫顽力机制可用发动场理论解释，且与实际相符较好。探讨了热压/热流变磁体各向异性的形成，展示了热退磁过程中烧结和热压/热流变磁体畴结构的演变规律。制备出最大磁能积约为424kJ/m3的各向异性纳米晶NdFeB磁体，研究表明，各向异性的产生主要源于再结晶过程中晶粒的择优生长和通过边界液相所促进的晶粒滑移和旋转。揭示出高性能各向异性纳米晶NdFeB磁体的典型磁畴结构是一种交换耦合畴。交换耦合畴的温度依赖关系是影响磁体使用温度的主要因素。

Abstract:: In this paper, we review recent research advance on coercivity mechanism of high performance NdFeB permanent magnets. Influence of fabrication process on the coercivity of the magnets is discussed. In particular, the correlation between microstructure and coercivity is investigated for the magnets prepared by using binary main phase alloy technique. The coercivity mechanism of the magnets prepared by traditional powder metallurgical method or binary alloy technique is based on the starting field theory, and the theoretical result is consistent with the experimental one. Furthermore, the formation mechanism of magnetic anisotropy of hot deformed NdFeB magnets is also discussed. The evolution of magnetic domains of sintered and hot deformed NdFeB magnets during thermal demagnetization process is presented. High performance anisotropic nanocomposite NdFeB magnets with (BH)m of 424 kJ/m3 are prepared. The formation of anisotropy of the magnets is expected as the anisotropic grow up of grains and their rotation and slicing. The magnetic microstructures of the magnets are typical interaction domains. The results show that both microstructures and magnetic properties are strongly correlated to optimum coercivity mechanisms for NdFeB magnets.