Experimental and theoretical investigations on the Y substituted and Cu doped nanocrystalline Ce–Fe–B alloys with enhanced hard magnetic properties and cost‐effectiveness

Abstract Enhancing the hard magnetic properties of Ce–Fe–B‐based magnets remains a significant challenge due to the REFe 2 (RE = rare earth) phase precipitation. Here, Y substitution for Ce and Cu doping is employed to suppress REFe 2 formation and optimize the intrinsic properties of RE 2 Fe 14 B phase. Partial substitution of Ce by Y significantly improves the magnetic properties and thermal stability of (Ce 1− x Y x ) 17 Fe 78 B 6 ( x = 0–0.8, at%) alloys. First‐principles calculations reveal that Y substitution destabilizes the REFe 2 phase, thus inhibiting its formation. Notably, at substitution levels exceeding x > 0.4, the residual REFe 2 phase undergoes a magnetic transition from paramagnetic to ferromagnetic behavior. Subsequent Cu doping in (Ce 0.5 Y 0.5 ) 17 Fe 77.6 Cu 0.4 B 6 alloys further destabilizes the REFe 2 phase and transforms aggregated bulk phases into intergranular structures. This microstructural modification facilitates magnetic decoupling, yielding enhanced magnetic properties with coercivity of 435 kA m −1 , remanence of 0.67 T and maximum energy product of 65.2 kJ m −3 . Micromagnetic simulations confirm the positive roles of tailoring the distribution and magnetic behavior of the REFe 2 phase in enhancing coercivity. Finally, the nanocrystalline (Ce 0.5 Y 0.5 ) 17 Fe 77.6 Cu 0.4 B 6 powders synthesized via industrial over‐quenching/annealing demonstrate a high performance/cost ratio, highlighting their significant potential for cost‐effective permanent magnet applications.