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.