钐钴合金等温时效过程中胞状组织结构的透射电镜表征

SmCo高温永磁体的磁性能与其特有的胞状组织结构密切相关,等温时效过程是胞状组织结构形成的主要阶段.采用透射电子显微镜(TEM)对2∶17型SmCo合金等温时效过程中的物相结构进行了表征,阐述了胞状组织结构的TEM测试方法.结果表明,通过特定晶带轴的选取,借助选区电子衍射和暗场像,可以对固溶体中的纳米尺度短程有序化微区和时效初期的胞状组织结构胚芽进行精确表征.结合高分辨分析,可以进一步对2∶17R相的有序化转变和胞状组织结构的生长进行分析,并证明时效保温阶段结束时已形成1∶5H、2∶17R、1∶3R三相共存的胞状组织结构.

Characterization on Cellular Structure of SmCo Magnets During Isothermal Aging Using Transmission Electron Microscopy

The magnetic properties of SmCo magnets are closely related to its unique cellular structure, and the isothermal aging process is the main stage of the formation of the cellular structure. The microstructure evolution of 2:17-type SmCo magnets during isothermal aging were characterized using transmission electron microscopy (TEM), and the TEM analysis method of cellular structure was described. The results showed that via selected area electron diffraction (SAED) and dark field analyses under certain zone axis, nanoscale short-range ordered micro-domains in the solution precursor and the embryos of cellular structure at the early stage of aging can be characterized. Combining high resolution transmission electron microscopy (HRTEM), the ordering transformation of 2:17R phase and the growth of cellular structure can be further analyzed, and a composite structure containing 1:5H, 2:17R and 1:3R phases are formed when the isothermal aging process is completed.