放电等离子烧结NdFeB永磁材料的显微组织研究

Study on Microstructure of NdFeB Magnet Prepared by Spark Plasma Sintering

采用放电等离子烧结技术制备了Nd15Dy1.2Fe余Al0.8B6永磁材料。通过扫描电镜和透射电镜观察和磁性能测试,研究了不同烧结温度和回火处理后的磁体显微组织及其对磁性能的影响。结果表明:在烧结温度为810℃时,可获得均匀细小的显微组织,通过回火处理能优化磁体显微组织,改善富钕相分布,从而达到提高磁性能的目的。同时,选区电子衍射研究发现,回火处理使三角晶界处富钕相的晶体结构由近似双六方结构转变为面心立方结构。

Nd15Dy1.2Feba1Al0.8B6 permanent magnets were prepared by the spark plasma sintering （SPS） technique. The effects of microstructures of NdFeB sintered at the different temperatures and tempered on magnetic properties were studied using SEM and TEM observation. The results show that the magnet sintered at 810 ℃ have the uniform microstructure with fine grain size, and the magnet microstructure can be optimized, the Nd-rich phase distribution can be improved by tempering, resulting in improving the magnetic properties. Furthermore, selected-area electron diffraction （SAD） reveal that the close to double hexagonal （dhcp） crystal structure of Nd-rich phase will be converted into face centered cubic （fcc） structure at the triple junction site through tempering .