HDDR各向异性钕铁硼磁粉的矫顽力通常介于10 kOe-13 kOe之间，最高使用温度不超过100℃，应用受限。添加镝可提高其矫顽力和温度特性，但是镝资源稀缺且价格昂贵，因此迫切需要开发无重稀土且具有高矫顽力的HDDR各向异性磁粉。我们首次发现在HDDR磁粉表面扩散低熔点的合金，可将磁粉的矫顽力由13 kOe提高到18 kOe，并可明显改善磁粉的温度特性。为了把该方法推向实用化，在本项目中我们将在深入研究扩散处理前后HDDR磁粉微观结构变化及其磁硬化机制的基础上，优选合金的类型和成分以及真空扩散热处理制度，实现在尽可能少牺牲磁粉剩磁的基础上，大幅提高磁粉的矫顽力和温度特性。最后我们也将通过优化HDDR磁粉制备工艺和相应调整扩散处理工艺相结合，探索制备具有高综合磁性能HDDR磁粉的可能性。本工作将有助于研究和开发高性能的各向异性粘结磁体，促进电机的小型化和高性能化，为建设低碳经济做贡献。

The coercivity of anisotropic HDDR Nd2Fe14B-type magnetic powders is generally between 10 kOe-13 kOe, and the heat resistance temperature is less than 100℃.Diffusion of Dy into the powders is helpful for improving the coercivity and thermal stability, but the heavy rare-earth metal is rare and expensive. Therefore, it is very important for developing the heavy rare-earth-free anisotropic HDDR powders with high coercivity. We found for the first time that the coercivity of HDDR powders can be enhanced from 13 kOe to 18 kOe by the diffusion of an alloy with a low melting point, and the corresponding thermal stability can be improved. In order to make this method be effective for preparing anisotropic powders with high coercivity and good thermal stability, the following work will be done in our study: .firstly, the microstructural changes and the coercivity mechanism of the anisotropic powders before and after the diffusion heat treatment will be investigated. Secondly, the type and composition of the alloy and the diffusion heat treatment parameters will be optimized to prepare the HDDR powders with high coercivity, good thermal stability and moderate remanence. Finally, the possibility of preparing the HDDR powders with high magnetic properties will be investigated by the combination of optimizing the HDDR process and the subsequent diffusion treatment parameters. Our study is helpful for developing the anisotropic bonded magnet with high magnetic performance, and is also beneficial to the minimization of electrical motor.