Microstructure and magnetic performance of Nd–Y–Ce–Fe–B sintered magnets after annealing

Annealing has been widely recognized as a crucial approach to modify the microstructure and enhance the coercivity of Nd–Fe–B magnets. However, in the context of Nd–Y–Ce–Fe–B magnets with multiple rare earths (REs) exhibiting different diffusion behaviors, annealing effects on the magnetic properties become more complicated and remain unknown. In present work, through a comparative study between as-sintered and annealed Nd–Y–Ce–Fe–B magnet upon 50 wt% Y–Ce co-substitution of total REs, we found that annealing process surprisingly enhances the remanence from 1.17 to 1.20 T, with simultaneous coercivity increment from 612.9 to 660.7 kA·m⁻¹, resulting in drastically improved maximum energy product from 242.0 to 263.5 kJ·m⁻³. Such a peculiar remanence enhancement is closely correlated to the preferential Y/Nd infiltration into RE₂Fe₁₄B main phase and Ce segregation into REFe₂ intergranular phase, which consequently improve the intrinsic magnetism, as evaluated by Curie temperature (T_C), saturation magnetic polarization (J_S) and magnetocrystalline anisotropy field (H_A). Present work delights that different metallurgical behaviors of Nd/Y/Ce exert influential effects on the intrinsic and extrinsic magnetic properties and provide a novel approach toward high-performance 2:14:1-type permanent magnets based on abundant RE mixtures.