快淬TbCu7型SmFe合金中空位的分布特征、形成机制及调控

Owing to the high magnetic property and heat corrosion resistance, the TbCu7-type SmFeN compounds are considered as a potential permanent magnet materials, which substitute for the melt-spun NdFeB magnetic powders. Based on the earlier work, the applicant and his co-workers find there exists an numerous vacancy defects in the TbCu7-type melt-spun SmFe alloys. However, the knowledge of vacancy on their crystal structure, phase structural stability and magnetic performance after nitriding is still controversial. In view of the above questions, the contents and distributions of the defects are analyzed by XRD-Rietveld, XPS, HRTEM, PAT .etc; the first-principles calculations are used to explore the influence of vacancy on the phase structural stability and magnetic performance after nitriding. Then, the segregation and migration of vacancies are adjusted by the adding other elements or heat treatment. Meanwhile, the correlation between the distribution of vacancies and nitriding rate is studied. Finally, an effective way to solve those problems and control the vacancy defects is established according to the relationships between the quenching rate, alloy components, heat-treatment and vacancy defects. Based on the above results, a new preparation method is exploited in order to prepare the TbCu7-type SmFeN melt-spun magnetic powders with high performance and stability.

快淬TbCu7型SmFeN化合物具有磁性能高、耐热耐蚀性好等特点，被认为是最有可能替代现有快淬NdFeB磁粉的一种新型永磁材料。申请人所在课题组研究发现快淬TbCu7型SmFe合金晶体结构中存在大量的空位缺陷。然而，空位对合金晶体结构、相稳定性及渗氮后的磁性能产生何种影响目前仍不清楚，且国内外鲜有报道。针对上述问题，项目拟采用XRD-Rietveld、XPS、HRTEM、PAT等手段研究快淬SmFe合金中空位的分布特征及形成机制；基于第一性原理研究空位对合金相结构及渗氮后磁性能的影响规律；通过添加元素、热处理等方法对空位的含量、迁移及分布进行调控。通过研究，揭示快淬条件、成分及热处理与SmFe合金中空位缺陷之间的内在关系，并掌握空位的有效调控手段，最终为提高TbCu7型SmFeN永磁材料性能提供新的思路与理论指导。

快淬TbCu7型SmFeN化合物具有磁性能高、耐热耐蚀性好等特点，被认为是最有可能替代现有快淬NdFeB磁粉的一种新型永磁材料。通过本课题研究发现快淬TbCu7型SmFe合金晶体结构中存在大量的空位缺陷。项目采用XRD-Rietveld、HRTEM、等手段研究快淬SmFe合金中空位的含量及形成机制，其中空位看作“溶质”， TbCu7 结构对“空位溶质”有一定“溶解度”；通过添加Co、Si、B等元素、发现小元素原子Si、B等掺杂可以显著提高TbCu7结构的稳定性，而高Co样品内部空位含量高于低Co样品，这与小元素原子的在晶格中的占位有直接的关系。该结果为TbCu7型SmFeN永磁材料的成分设计及性能提高提供了新的思路。