Coercivity enhancement of hot-deformed Ce-Fe-B magnets by grain boundary infiltration of Nd-Cu eutectic alloy

The coercivity of hot-deformed Ce-Fe-B magnet was substantially improved from similar to 8 x 10(-4) to similar to 0.7 T by the grain boundary infiltration of Nd-Cu eutectic alloy. Transmission electron microscopy have shown the formation of (NdxCe1-x)2Fe(14)B shell in Ce2Fe14B grains and the increase of rare earth elements in the intergranular phases after the process. The former enhances the anisotropy field of the shell region and the latter weakens intergranular exchange coupling. Micromagnetic simulations showed that the increase of the Nd content in the (NdxCe1-x)2Fe(14)B shell results in only a slight increase in coercivity for ferromagnetic intergranular phase. This explains the minor increment of coercivity of only similar to 0.2 T for the increased amount of the Nd-Cu infiltration from 10 wt% to 40 wt%. For further increase of the coercivity, exchange decoupling by increasing the rare earth content in the intergranular phase is predicted to be effective. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.