Combining grain boundary diffusion and segmentation: A novel production route for resource-efficient Nd-Fe-B magnets

To enhance coercivity in high-performance Nd-Fe-B magnets, resource critical heavy rare earth elements Dy and Tb are used in the grain boundary diffusion process (GBDP). However, GBDP is limited to thin magnets, typically around 4 mm which restricts their applications. Here, we report a novel processing route by combining the GBDP process with a magnet stacking architecture using a < 10 μm thin low-melting multi-element Tb₁₀Pr₆₀Al₁₀Cu₁₀Ga₁₀ alloy which has now a dual function: it acts as a binder between the magnet segments and is at the same time an efficient source for core-shell formation on the individual crystallite level. This not only enables production of magnets with any thickness without losing performance, but also paves the way for resource efficiency using cheap and abundant light rare earth Cerium in hybrid magnets by strategically stacking different grades with tailored chemical compositions resulting in a unique macroscopic magnetic hardening.