Comparison on the Coercivity Enhancement of Hot-Deformed NdFeB Magnets by Doping Ce₈₀M_20-xZn_x (M = Cu or Al; x=020) Alloy Powders

Coercivity enhancement of hot-deformed (HD) NdFeB magnets by doping low-cost Ce80M20-xZnx ( M = Cu and Al; x = 0-20) alloy powders is compared. By doping Ce(80)M(20-x)Znx powders, coercivity (i H-c) is increased from 15.0 kOe for the as-upset magnet to 17.2-18.5 kOe for M = Cu and 17.0-19.1 kOe for M = Al, respectively. Compared to the magnet doped with Ce80Al20 (H-i(c) = 17.0 kOe), the magnet doped with Ce80Al10Zn10 exhibits a higher H-i(c) of 19.1 kOe. In addition, the grain morphology of the magnet doped with Ce80Al10Zn10 is more platelet-like than that doped with Ce80Al20. The platelet grain morphology contributes to the good (00L) texture, and thus, higher remanence is obtained. Microstructure and element analysis show Ce, Al, Cu, and Zn prefer to distribute at grain boundary, which can strengthen the decoupling effect between the adjacent Nd2Fe14B (2:14:1) grains. Almost unchanged Curie temperature (T-C) of 2:14:1 phase for the magnet doped with Ce80Al10Zn10 also indicates Ce mostly distributes at the grain boundary. The effect of doping Ce-Al-Zn-containing alloys on the coercivity enhancement and mechanism for HD NdFeB magnets is also discussed in this work.