Simultaneously enhancing coercivity and remanence of hot-deformed Nd-Fe-B magnets by flake copper powder assisted DyF3 interflake addition

Abstract

It is still a challenge to simultaneously enhance coercivity (H_cj) and remanence (J_r) of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma. Here, we achieved this balance between H_cj and J_r by flake Cu powder assisted DyF₃ interflake addition. The H_cj increases from 1218 to 1496 kA/m and J_r increases from 1.32 to 1.34 T compared with the original magnet. Results show that the width of coarse grain layers reduces because of the introduction of flake Cu, which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains. The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_r. Additionally, the aggregation regions of rare earth rich (RE-rich) phase reduce and the betterment of the microstructure is another reason for the enhancement of J_r in the flake Cu aided DyF₃ hot-deformed magnet. This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.