We have published our latest results on the recycling of grain boundary diffusion (GBD) magnets in Acta Materialia. GBD magnets are characterized by a special microstructure (core-shell), which makes it possible to produce magnets with high coercivity and thus higher operating temperature while at the same time optimizing the amount of particularly critical heavy rare earths (Tb, Dy) required for this purpose. Such magnets are mainly used in traction motors of electric vehicles, and the demand for such resource-optimized high-performance magnets will increase in the near future.

Our research has shown that the special microstructure of these magnets is negatively affected by the functional recycling process using hydrogen embrittlement and re-sintering. However, we have managed to successfully recycle these magnets and restore the core-shell structure and thus the magnetic properties in the recycled magnets.

Mario Schönfeldt, Jürgen Rossa, Konrad Opelt, Kilian Schäfer, Lukas Schäfer, Fernando Maccari, Matic Jovičević-Klug, Tim M. Schwarz, Chi-Chia Lin, Mahmudul Hasan, Jürgen Gassmann, Dierk Raabe, Oliver Gutfleisch,
Functional recycling of grain boundary diffusion processed Nd-Fe-B sintered magnets,
Acta Materialia 283 (2025) 120532.

https://doi.org/10.1016/j.actamat.2024.120532.

The open access paper is available here.