Novel PrNd-Lean Ce-Based R₂Fe₁₄B Permanent Magnets With High Performance

Abstract

In this article, the phase compositions, microstructures, and magnetic properties of PrNd-free Ce-Fe-B-based sintered magnets with the nominal composition of (Ce0.78Y0.17La0.05)16.28Febal.B7.44M1.94 (at.%: M = Co, Al, Cu, and Nb) have been investigated. It shows that a lamellar crystalline structure is formed in the Ce-Fe-B-based strip casting (SC) alloy. The Y-substituted Ce-Fe-B-based SC alloy is mainly composed of R2Fe14B and RFe2 phases. It suggests that Y substitution is helpful for depressing the $\alpha $ -Fe phase generated in the SC alloy. The island-like intermediate phases exist in the RFe2 region, which are probably caused by the incomplete peritectic reaction during alloy solidification. The Curie temperature $T_{\mathrm {c}}$ of the Y-substituted Ce-Fe-B-based alloy is about 463 K, which is higher than that of the Ce2Fe14B compound ( $T_{\mathrm {c}} =424$ K). For the experimental Ce-Fe-B-based sintered magnet without PrNd addition, the remanence $B_{\mathrm {r}}$ of 8.31 kG, the coercivity $H_{\mathrm {cj}}$ of 0.92 kOe, and the maximum energy product (BH)max of 5.30 MGOe have been obtained. A good combination of coercivity $H_{\mathrm {cj}}$ (= 5.57 kOe) and maximum energy product (BH)max (= 20.17 MGOe) has been achieved in the Ce-Fe-B-based blended magnet with PrNd/ $\sum $ RE = 25% prepared using a binary main phase (BMP) method. The heterogeneous elemental distributions and microstructure characteristics of the BMP magnet are also analyzed.