Strategy for Co‐Enhancement of Remanence–Coercivity of RE‐Fe‐B Sintered Magnets with High Ce‐Content: Appropriate La Substitution

Abstract The development of low‐cost RE‐Fe‐B sintered magnets with large La/Ce content is of great significance for the balanced utilization of rare earth (RE) resources, but it is limited by reduced magnetic properties. In this work, the coercivity (H_cj), remanence (B_r), maximum energy product [(BH)_max], and temperature stability are simultaneously enhanced for magnets with LaCe accounting for 40 wt% of the total RE. The synergistic regulation of the REFe₂ phase, Ce‐valence, and grain boundaries (GBs) in RE‐Fe‐B sintered magnets is realized for the first time by introducing appropriate La elements. The La elements inhibit the generation of the REFe₂ phase and tend to stay in the triple junctions, promoting the segregation of the RE/Cu/Ga elements and contributing to the formation of Ce/Nd/Cu/Ga‐rich continuous thicker lamellar GBs, and as a result, weakening the detrimental effect on HA caused by La element substitution and enhancing H_cj. In addition, partial La atoms entering the RE₂Fe₁₄B phase are beneficial for improving the B_r and temperature stability of the magnets and promoting the Ce³⁺ ion ratio, which also provides additional benefit for B_r. The findings provide an effective and feasible way to co‐enhance the remanence and coercivity of RE‐Fe‐B sintered magnets with high Ce content.