High‐Remanence Fe‐Rich 2:17‐Type Sm–Co Sintered Magnets Mediated via Multiscale Microstructure

Realizing high remanence in Fe‐rich 2:17‐type Sm–Co sintered magnets remains a challenge when Fe content exceeds 23 wt%. Herein, a record remanence of 12.42 kGs is obtained by multiscale microstructure regulation strategy, based on co‐optimization from pulverizing treatment to solid solution and aging treatment. The density of sintered magnets is significantly enhanced by refining magnetic powders using ball milling to reduce porosity. Grain boundary precipitation phase is eliminated via prolonging solid solution time, together with reduced Fe concentration in the cell boundaries, due to increased proportion of defected 1:3R planar Z phase. Furthermore, the proportion of 1:3R planar Z phase is increased by greatly reducing the 2:17R’ phase during appropriately isothermal aging temperature to reduce Fe concentration in cell boundaries and the remanence of the magnet increases. The studies deepen the understanding of the correlation among process, microstructure, and remanence, guiding the preparation of Fe‐rich 2:17‐type Sm–Co sintered magnets with high magnetic performance.