Exploring Sintered Fe-(Ce, Nd)-B with High Degree of Cerium Substitution as Potential Gap Magnet

The more effective use of readily available Ce in FeNdB sintered magnets is an important step towards more resource-efficient, sustainable, and cost-effective permanent magnets. These magnets have the potential to bridge the gap between high-performance FeNdB and hard ferrite magnets. However, for higher degrees of cerium substitution (>25%), the magnetic properties deteriorate due to the lower intrinsic magnetic properties of Fe₁₄Ce₂B and the formation of the Laves phase Fe₂Ce in the grain boundaries. In this paper, sintered magnets with the composition Fe70.9-(Ce_xNd_1-x)18.8-B5.8-M4.5 (M = Co, Ti, Al, Ga, and Cu; with Ti, Al, Ga, and Cu less than 2.0 at% in total and Co_bal; x = 0.5 and 0.75) were fabricated and analyzed. It was possible to obtain coercive fields for higher degrees of Ce substitution, which previous commercially available magnets have only shown for significantly lower degrees of Ce substitution. For x = 0.5, coercivity, remanence, and maximum energy product of µ₀H_c = 1.29 T (H_c = 1026 kA/m), J_r = 1.02 T, and (BH)_max = 176.5 kJ/m³ were achieved at room temperature for x = 0.75 µ₀H_c = 0.72 T (H_c = 573 kA/m), J_r = 0.80 T, and (BH)_max = 114.5 kJ/m³, respectively.