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Ce substitution of Nd in FeNdB sintered magnets is very interesting for reasons of resource efficiency, sustainability and costs. However, the magnetic properties of high Ce‐content magnets are poor. This is mainly due to the lower values of intrinsic magnetic properties of Fe14Ce2B compared to Fe14Nd2B as well as the Laves phase Fe2Ce, which is formed in the grain boundaries and forms flat aggregates for higher Ce‐content. In this article, sintered magnets with 75 at% degree of substitution of the composition Fe70.9–[(Ce1−xLax)0.75Nd0.25]18.8–B5.8–M4.5 (M = Co, Ti, Al, Ga, Cu, 0 ≤ x ≤ 0.3) are produced and analyzed. It is shown that a new rare earth rich grain boundary phase is formed adding La and that the Laves phase fraction can be reduced by up to 85%. With increasing La content, the remanence and Curie temperature increase and the temperature coefficient of Hc improves. A coercivity, remanence, and maximum energy density of up to μ0Hc = 0.74 T, Jr = 0.98 T, and (BH)max = 139.9 kJ m−3 have been achieved. [ABSTRACT FROM AUTHOR]

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• High entropy design for RE 2 Fe 14 B with five rare earth elements La/Ce/Pr/Nd/Y. • The magnets have a high RE 2 Fe 14 B melting temperature, less REFe 2 and fine grains. • (BH) max reached 33.48 MGOe with 60 wt% La/Ce/Y substituted Pr/Nd. • Pr/Nd-lean sintered magnets were prepared with single main phase process. In this study, single main phase (SMP) magnets with high-entropy RE 2 Fe 14 B were prepared, which contained La, Ce, Pr, Nd and Y. The microstructure and properties of the magnets were studied. The results show that the magnets with high entropy design have a higher melting temperature (T m) of RE 2 Fe 14 B (1189.5℃), less REFe 2 and finer grains (mean grain size: 4.51 μm) compared with binary main phase (BMP) magnets of (LaCe)-Fe-B mixed with (PrNd)-Fe-B. This is mainly due to the high entropy effect, lattice distortion effect and sluggish diffusion from the high-entropy RE 2 Fe 14 B, as well as the synergism of the rare earth (RE) elements. The properties of the magnets are enhanced, especially the magnetic properties. Maximum energy product (BH) max of 33.48 MGOe is achieved with only 40 wt% Pr/Nd in total RE. This work provides a valuable method to obtain RE-Fe-B magnets with high cost performance. [ABSTRACT FROM AUTHOR]