NdFeB/SmCo5纳米复合永磁体的界面控制、性能及机理研究

In order to solve the problem of poor temperature stability for NdFeB magnets, and satisfy the requirements for magnets with both high performance and high temperature stability in the demanding applications of high efficiency, energy saving, emission reduction, etc, the project proposes NdFeB/SmCo5 novel nanocomposite permanent magnet fabricated by the spark plasma sintering - hot deformation method based on the performance complementation effect, technical compatibility and composite enhancement effect. The problems on the key theory and process technology of its interface control, magnetic mechanism and so on are to be investigated. According to Miedema theory, the possible phase selection law of the composite system is predicted. The interface structure and chemistry are modulated through sintering process and interfacial modification, and then the laws of interfacial reaction and phase formation are revealed by combining with the thermokinetics of interfacial reaction, consequently clarifying the interface control mechanism. On the basis of the demagnetization curve and Henkel plot, the researches of magnetic interactions between grains and its relationship with the microstructures of grain and interface are carried out, and the magnetic composite effect theory is established. The magnetization and magnetization reversal behaviors of composite magnets are investigated to clarify the magnetization reversal mechanism and coercivity mechanism combined with the micromagnetic numerical simulation. The microstructure control law of composite magnets via process is summarized and analyzed, thereby establishing the structure-property relationship between the microstructure and magnetic properties and temperature characteristics. The investigation of this project will provide the important theoretical basis and technical approach for exploring and developing novel rare earth permanent magnet materials with high performance and high temperature stability.

为解决NdFeB磁体温度稳定性差的问题，满足高效、节能、减排等苛刻应用领域对兼具高性能和高温度稳定性磁体的需求，本项目基于性能互补效应、工艺相容性与复合增强效应提出放电等离子烧结-热变形NdFeB/SmCo5新型纳米复合永磁体，拟研究其界面控制、磁学机理等关键理论与工艺技术问题。基于Miedema理论，预测复合体系可能的相选择规律；通过烧结工艺与界面改性调控复合磁体的界面结构与界面化学，结合界面反应热动力学，揭示界面反应与成相规律，阐明界面控制机理。基于退磁曲线与Henkel图，研究晶粒间磁相互作用及其与晶粒和界面微结构的关系，建立磁复合效应理论。研究复合磁体的磁化与反磁化行为，结合微磁学数值模拟，阐明其反磁化机制和矫顽力机理。总结分析复合磁体的微结构工艺控制规律，建立微结构与磁性能和温度特性的构效关系。本项目研究将为探索开发高性能高温度稳定性的新型稀土永磁材料提供重要理论依据和技术途径。

本项目为解决NdFeB磁体温度稳定性差的问题，满足高效、节能、减排等苛刻应用领域对兼具高性能和高温度稳定性磁体的需求，研究了NdFeB/SmCo5复合永磁体的界面控制、磁学机理等关键理论与工艺技术问题。基于Miedema理论，计算得到了NdFeB/SmCo5复合体系可能反应形成的合金相的热力学数据，获得了可能的相选择规律，揭示了Nd2Fe14B与SmCo5相间的界面反应规律和机理，阐明了界面弱磁中间相的形成规律；设计了非磁性的低熔点Pr68Cu32界面改性相，探索了磁体界面结构与相组成，结合界面反应热动力学，揭示了其对NdFeB/SmCo5复合磁体中两硬磁相的界面调控规律，阐明了界面控制机理；分析了NdFeB/SmCo5纳米复合磁体中硬磁晶粒间的磁相互作用及其与微观结构的相关性，建立了不同条件下硬磁晶粒间的磁耦合效应理论；研究了不同温度下NdFeB/SmCo5复合磁体的磁学特性，揭示了复合磁体温度稳定性变化规律，结合微磁学理论，建立了复合磁体矫顽力、硬磁相尺度与温度的关系规律，阐明了复合磁体的矫顽力机理；分析了NdFeB和SmCo5的相结构、微观形貌与分布，得出了微观结构工艺控制规律，建立了工艺-结构-性能的关联关系。本项目按计划完成了预期研究目标，研究成果将为探索开发高性能高温度稳定性的新型稀土永磁材料提供重要理论依据和参考。