Using Recycled Nanocrystalline HDDR Powders in the Additive Manufacturing of Bonded Nd-Fe-B Magnets

Additive manufacturing (AM) has recently been shown as a potential processing method to obtain bonded Nd-Fe-B magnets. Meanwhile, recycling is gaining prominence due to the increasing availability of end-of-life magnets. Thus far, most efforts have aimed to obtain sintered magnets via the magnet-to-magnet approach, but recycling strategies can also be rethought toward the fabrication of bonded magnets instead of sintered ones. Our primary objective is to investigate the fabrication of bonded magnets via AM, using feedstocks composed of nanocrystalline powders obtained from scrap. For that purpose, Nd-Fe-B scrap magnets were subjected to hydrogen processing to obtain nanocrystalline powders. The nanocrystalline powders were then used to prepare feedstocks, from which 3-D print recycled bonded magnets were fabricated via two AM techniques: laser powder bed fusion (LPBF) and stereolithography. For both techniques, the recycled nanocrystalline powders were shown to be adequate, with mean values of coercivity and remanence equal to 750 kA/m and 705 mT, respectively. By using feedstocks composed of such powders, we were able to successfully obtain complex shape magnets via AM.