Effects of Ce content on microstructure evolution and magnetic properties for hot deformed Ce–Fe–B magnets

Abstract

Understanding the evolution of phase and microstructure is a critical step to prepare high performance magnets. In this work, hot deformed (HD) Ce–Fe–B magnets with different Ce contents are prepared. The results demonstrate that the content of CeFe2 phase is enhanced with increasing Ce content. And its distribution changes from the sporadic distribution for Ce13.5Fe81B5.5 magnet to the mixed distribution consisting of large strip-shaped grains and dispersed distribution around main phase for Ce17Fe78B5 magnet to the nearly complete dispersed distribution for Ce21Fe74B5 magnet. These CeFe2 phase around main phase can increase magnetic isolation effect, improving the coercivity of HD magnet. In addition, it is found that a large amount of CeFe2 phase and equiaxed 2:14:1 phase grain without c-axis orientation surround each other, indicating that the CeFe2 phase is not favorable to the formation of c-axis orientation. Elemental metallurgical behavior reveals that Pr and Cu elements are segregated between platelet-shaped main phase grains, and however, for equiaxed grain region, Pr and Cu elements are enriched in CeFe2 phase. Based on the grain boundary diffusion (GBD), the coercivity, remanence and magnetic energy product are all improved significantly, increasing by 287%, 74%, and 371%, respectively, which is attributed to the formed (Pr, Ce)2Fe14B phase and increased magnetic isolation effects.