Novel PrNd-Lean Ce-Based R_2Fe_(14)B Permanent Magnets With High Performance

摘要

In this article, the phase compositions, microstructures, and magnetic properties of PrNd-free Ce-Fe-B-based sintered magnets with the nominal composition of (Ce_(0.78)Y_(0.17)La_(0.05))_(16.28) Fe_(bal.)B_(7.44)M_(1.94) (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 R_2Fe_(14)B and RFe_2 phases. It suggests that Y substitution is helpful for depressing the α-Fe phase generated in the SC alloy. The island-like intermediate phases exist in the RFe_2 region, which are probably caused by the incomplete peritectic reaction during alloy solidification. The Curie temperature T_c of the Y-substituted Ce-Fe-B-based alloy is about 463 K, which is higher than that of the Ce_2Fe_(14)B compound (T_c = 424 K). For the experimental Ce-Fe-B-based sintered magnet without PrNd addition, the remanence B_r of 8.31 kG, the coercivity H_(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_(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/ΣRE = 25 prepared using a binary main phase (BMP) method. The heterogeneous elemental distributions and microstructure characteristics of the BMP magnet are also analyzed.