Magnetic properties, thermal stability, and microstructure of spark plasma sintered multi-main-phase Nd-Ce-Fe-B magnet with PrCu addition

Nanostructured multi-main-phase (MMP) Nd-Ce-Fe-B magnet produced by melt-spinning powders has great potential for achieving high performance. However, the inferior intrinsic properties of the Ce₂Fe₁₄B phase lead to the low coercivity and thermal stability of this magnet. In this study, low-melting-point Pr₆₈Cu₃₂ powders were introduced into nanostructured MMP magnet through intergranular addition to further improve its coercivity and thermal stability. When only 2 wt% Pr₆₈Cu₃₂ was added, the intrinsic coercivity H_cj and thermal stability were significantly improved with a slight reduction in the remanence B_r and the maximum energy product (BH)_max. The microstructure evolution of MMP magnet with adding Pr₆₈Cu₃₂ was revealed by microstructural and compositional characterization and thermodynamic calculation, and a schematic model was proposed. Furthermore, mechanisms underlying changes in magnetic properties were systematically analyzed by combining micromagnetic simulation.