Effects of Nb microalloying on the magnetic properties and microstructure of Fe-Si-B-P-Cu-Nb nanocrystalline alloys prepared with pure and industrial raw materials

Fe-based nanocrystalline alloys with high saturation magnetic flux density (Bs) and low coercivity (Hc) are highly desirable, especially if they can be prepared with industrial raw materials (IRMs). Here, Fe82.3Si4B9P4Cu0.7 and Fe82.3Si4B9P3Cu0.7Nb1 nanocrystalline ribbons were prepared with IRMs and pure raw materials (PRMs). It was found that Nb microalloying broadens the annealing process window of the rib-bons due to the suppressed precipitation of Fe(B, P) phase. In addition, the soft magnetic properties of the Fe82.3Si4B9P3Cu0.7Nb1 ribbons prepared with IRMs are insensitive to impurities and surface-crystallized layer. Compared to the PRMs-prepared ribbons, the IRMs increase the Hc of the Nb-free ribbons, whereas having little effect on the Hc of the Nb-doped ribbons with dendritic-crystallites in the surface layer. These results originate from the former forming coarse alpha-Fe grains and narrow magnetic domains, while the latter mainly forming fine alpha-Fe grains and broad magnetic domains. This work provides a valuable reference for the development and industrialization of nanocrystalline alloys with high Bs and low Hc.(c) 2022 Elsevier B.V. All rights reserved.