Relationship between Hydrogen Pressure and Temperature for Recombination Reactions in the HDDR Processing of Ce–Fe–B Alloys

Abstract

In recent years, to reduce manufacturing costs and alleviate the rare-earth supply/demand imbalance in the Nd-Fe-B magnet market, researchers have actively pursued the development of (Nd,Ce)-Fe-B magnets, in which Nd is replaced by Ce. In the present study, we focused on magnetic powders treated by the hydrogenation-disproportionation-desorption-recombination (HDDR) process and explored the relationship between the hydrogen pressure and temperature (P H2 -T curves) in the Ce-Fe-B system, which is essential for the development of (Nd,Ce)-Fe-B magnets. It was confirmed that the disproportionation and recombination reactions of both Ce 2 Fe 14 B and CeFe 2 take place in the Ce-Fe-B system. Furthermore, compared with Nd 2 Fe 14 B, the P H2 -T curve of Ce 2 Fe 14 B was found to be shifted to higher pressure and lower temperature, suggesting a corresponding shift in the HDDR conditions under which good magnetic properties can be obtained.