Investigation of the Impact of SmFeN Doping on the Anisotropic NdFeB/SmFeN Composite Magnets

By incorporating various types of permanent magnetic powders, composite magnets with cost-effectiveness and a wide range of magnetic properties can be achieved. In this study, the anisotropic composite magnets were fabricated using the hot press forming method, which involved blending neodymium iron boron (NdFeB) powder and samarium iron nitrogen (SmFeN) powder. The experiment demonstrated that the magnet density reaches its maximum point when the doping level of SmFeN reaches 20 wt.%, aligning remarkably well with the corresponding theoretical value of 19.22 wt.% achieved through a cubic stacking arrangement. In the absence of an applied magnetic field or under a sufficiently high oriented magnetic field (3 T), the remanence variation pattern in composite magnets doped with different amounts of SmFeN aligns consistently with the density pattern, yielding a maximum value of 20%. However, in the actual solidification process, the orientation field is insufficient (e.g., 1.5 T), necessitating a doping amount that exceeds the value corresponding to peak density by 28% to achieve optimal remanence. This observation suggests that the incorporation of a higher proportion of small-sized and relatively low coercivity SmFeN magnetic powder can effectively facilitate the rotational alignment of neighboring large-sized NdFeB magnetic powder under weak magnetic fields, thereby inducing a synergistic effect.