Understanding the element segregation and phase separation in the Ce-substituted Nd-(Fe,Co)-B based alloys

L.Z. Zhao (1, 2) , J.S. Zhang (1) , G. Ahmed (1) , X.F. Liao (1) , Z.W. Liu (1) , Jean-Marc Greneche (3)

1 SCUT - South China University of Technology [Guangzhou]
2 HDU - Hangzhou Dianzi University
3 IMMM - Institut des Molécules et Matériaux du Mans

Ce substituted Nd2Fe14B (2:14:1)-type permanent magnets have shown increasing potential in the applications due to their high properties/cost ratio. However, the element segregation and phase separation in the Ce substituted magnets have not been fully understood yet. In this work, (Nd1−xCex)25Fe40Co20Al4B11 alloys with high coercivities were prepared by copper mold casting. Based on detailed microstructure and composition analysis, the segregation of rare earth (RE) elements was observed in the as-cast alloys. Nd element prefers to enter into the 2:14:1 phase and the Ce element enter into the 1:2 phase. The existence of the 1:2 phase can promote the element segregation. The alloy shows an abnormal increase of coercivity from 641 kA/m for x = 0.2 to 863 kA/m for x = 0.3. This increase could be attributed to the phase separation of the 2:14:1 phase, which has been confirmed by the microstructural characterization. The present data provides useful information for exploring Ce-containing Nd-Fe-B magnets.

Domaines: Physique [physics]; Matière Condensée [cond-mat]

L.Z. Zhao, J.S. Zhang, G. Ahmed, X.F. Liao, Z.W. Liu, et al.. Understanding the element segregation and phase separation in the Ce-substituted Nd-(Fe,Co)-B based alloys. Scientific Reports, 2018, 8 (1), pp.6826. ⟨10.1038/s41598-018-25230-0⟩. ⟨hal-02120568⟩