Influence of colloidal surface-additivation with surfactant-free laser-generated metal nanoparticles on Nd-Fe-B permanent magnets produced by suction casting

The development of new powder feedstocks using nanoparticles (NPs) has the potential to enhance the functionality of as-built parts and overcome the limitations of current additive manufacturing (AM) techniques. This study investigated the impact of magnet microparticle feedstock modification by NPs on the microstructure and functionality of Nd-Fe-B-based permanent magnets made by suction casting. This casting method is known to at least partially mimic the melting and fast solidification steps inherent to metal powder-based AM techniques such as Laser Powder Bed Fusion. Two types of NPs, Ag, and ZrB2, were used, and their effects on grain size distribution and dendritic structure were evaluated. Ag NPs resulted in smaller, more uniform grain sizes and increased functionality, but only for loadings > 0.5 monolayers. ZrB2 resulted in uniformly distributed grain sizes at much lower mass loadings, with even more compact dendritic arms. The results show that feedstock powder surface modification with low melting point metal NPs can improve the microstructure and magnetic properties of permanent magnets produced by AM and highlight the potential of using NPs to develop new powder feedstocks for AM. With this, it provides insights for future research on optimizing materials for AM processes.