Effect of texture intensity on grain boundary diffusion in sintered NdFeB magnets

This study optimized grain texturing in magnets by adjusting the strength of the aligned magnetic field and investigated its impact on heavy rare earth (HRE) diffusion. By increasing the magnetic field strength significantly enhanced grain orientation, the (001) texture with an multiple of uniform distribution (MUD) of 25.59. Simultaneously, the triangular grain boundary (GB) phase decreased, replaced by continuous GB phases, while grain size reduced to 2.75 μm. After grain boundary diffusion, the magnets achieved a coercivity of 29.11 kOe, reflecting a 38% increase. This improvement stems from the thin, continuous GB phases, which facilitate efficient HRE diffusion. Additionally, smaller grains raised defect density, further enhancing diffusion pathways. The enhanced alignment of the magnetic field also improved stress uniformity, creating a sustained driving force for deeper HRE diffusion. This optimization transformed the shell layer from a thick, uniform structure to a thinner, inhomogeneous one, reducing HRE consumption while improving diffusion depth and efficiency. These advancements significantly enhance magnet performance, lower costs, and improve HRE utilization.