烧结钕铁硼磁体的晶界扩散技术因可以高效利用重稀土元素制备高矫顽力钕铁硼磁体而成为当前永磁材料领域的研究热点。晶界扩散后磁体的矫顽力呈梯度分布特征，而矫顽力梯度分布难以定量调控与测试表征的技术难点限制了对矫顽力梯度分布与宏观磁性能关系及其物理机制的深入认识。本项目拟借助真空热压扩散焊技术制备矫顽力梯度分布可控的复合钕铁硼磁体，系统研究磁体的宏观磁性能随矫顽力梯度分布大小和方向的演变规律，建立矫顽力梯度分布与宏观磁性能的关联性。同时，利用微磁学模拟构建具有不同矫顽力梯度分布特征的复合钕铁硼磁体模型，研究磁体模型的退磁行为对矫顽力梯度分布特征的依赖关系，从而揭示矫顽力梯度分布对宏观磁性能的影响规律及其物理机制。本项目的研究成果有助于深化对烧结钕铁硼磁体晶界扩散技术背后物理机制的认识，并为烧结钕铁硼磁体晶界扩散技术在应用过程中工艺参数优化设计提供理论指导。

The grain boundary diffusion process (GBDP) of sintered Nd-Fe-B magnets makes full use of heavy rare earth elements to produce Nd-Fe-B magnets with high coercivity, which has become a hot topic in the field of permanent magnet materials. After GBDP the coercivity gradient distribution appears in magnets, but the difficulties in regulating and measuring the coercivity gradient distribution limit the deep understanding between the coercivity gradient distribution and the macroscopic magnetic properties as well as the corresponding physical mechanism. This project intends to fabricate composite Nd-Fe-B magnets with controllable coercivity gradient distributions via the hot pressure diffusion welding under vacuum. The evolution of macroscopic magnetic properties with the magnitude and direction of the coercivity gradient distribution will be studied systematically, and the correlation between the coercivity gradient distribution and the macroscopic magnetic properties will be established. At the same time, composite Nd-Fe-B magnet models with different coercivity gradient distributions will be constructed using micromagnetic simulation, and the demagnetization behavior dependence of magnet models on the coercivity gradient distribution will be studied. The influence law and physical mechanism of the coercivity gradient distribution on the macroscopic magnetic properties will be revealed. The research results of this project will help to deepen the understanding of the physical mechanism behind the GBDP of sintered Nd-Fe-B magnets and provide theoretical guidance for the design and optimization of technological parameters of GBDP during application.