热变形SmCo5/Fe(Co)纳米复合永磁材料的晶界改性及[001]织构增强机制

SmCo5/Fe(Co) nanocomposite permanent magnetic materials are candidates for new generation permanent magnetic materials operated at elevated temperatures up to 500℃, which have the potential to be central materials of the area such as aircraft engine with high thrust-weight ratio and high precision satellite earth observation system. Theoretically, achievement of fully strong texture in the magnets may enhance the energy product by four times compared with the magnets without texture. However, strong texture is difficult to realize because the fine nanograins are easy to agglomerate, the [001]-texture of SmCo5/Fe(Co) nanocomposite permanent magnets prepared by existing technology is usually weak, which hinds the improvement of the magnetic properties. This project is based on our exploratory research of SmCo5/Fe(Co) nanocomposite magnets, a method of grain boundary modification will be adopted to enhance the [001]-texture of hot-deformed SmCo5/Fe(Co) nanocomposite permanent magnets. First, The phase structure, morphology and distribution of the grain boundary phase introduced by the addition of low-melting eutectics such as Sm-M (M=Ni、Zn etc.) will be studied. Second, The influence of grain boundary phase on the structure and chemistry of the interface between SmCo5 and Fe(Co) nanograins will be clarified. Third, The mechanism of enhanced texture in hot-deformed magnets by grain boundary modification will be revealed. Last but not the least, the effect of grain boundary modification on the magnetic properties will be clarified. The research results will develop the preparation theory and technology of high performance nanocomposite permanent magnetic materials.

SmCo5/Fe(Co)纳米复合永磁材料，作为潜在的新一代使用温度高达500℃的永磁材料，有望成为高推重比航空发动机和高精度卫星对地观测系统等领域的核心材料。理论上，完全强织构的实现可将永磁材料的磁能积增大到无织构时的4倍。然而，纳米晶易团聚导致强织构实现困难，现有技术制备的SmCo5/Fe(Co)纳米复合永磁体的[001]织构一般较弱，限制了其磁性能的提高。本项目拟在前期对SmCo5/Fe(Co)纳米复合磁体制备探索的基础上，采用晶界改性的方法增强热变形SmCo5/Fe(Co)纳米复合磁体的[001]织构，研究低熔点共晶合金Sm-M（M=Ni、Zn等）添加引入的晶界相的相结构、形态及分布，明确晶界相引入对SmCo5和Fe(Co)纳米晶的界面结构和化学的改性作用，揭示晶界改性对热变形磁体织构的增强作用机制，阐明晶界改性对磁体磁性能的影响规律，发展高性能纳米复合永磁材料的制备理论及技术。

航空航天、风力发电和新能源汽车等领域对使用温度较高的永磁材料提出明确需求，研发新一代高性能高使用温度的永磁材料十分迫切。本项目以潜在的新一代高性能高使用温度的永磁材料-SmCo/Fe(Co)纳米复合永磁材料为研究对象，系统地研究了粉体、热压磁体和热变形磁体的制备、相组成、微观结构和磁性能。采用向SmCo/Fe(Co)纳米复合永磁材料中引入Sm-M (M=Ni, Zn)低熔点共晶合金的方法，重点研究了Sm-M合金添加对SmCo/Fe(Co)纳米复合永磁材料的成分、微观结构和磁性能的影响规律。我们制备了SmCo/FeCo纳米复合永磁材料，其中硬磁相为SmCo5相或Sm2Co17相，软磁相为FeCo相，硬磁相和软磁相在磁体内部均匀分布，晶粒尺寸均在10 nm左右；探明了Sm-M（M=Ni、Zn）合金添加对SmCo/FeCo纳米复合永磁材料磁织构的影响规律，发现加入Sm-M合金后磁体中出现了较多的SmCo5相，有助于磁体的形变织构，热变形温度是影响SmCo/FeCo纳米复合永磁材料纳米晶晶粒择优取向生长的关键因素；揭示了Sm-M（M=Ni、Zn）合金添加对SmCo/FeCo纳米复合永磁材料矫顽力的增强机理，发现Sm-M合金添加稳定了强各向异性的SmCo5相，显著地提高了纳米复合磁体的矫顽力。基于本项目的研究成果，已发表SCI收录论文3篇，申请国家发明专利2项，参与制定国家标准1项。该项目的研究成果为发展高性能纳米复合永磁材料提供了理论和实验依据。