Improving the processability of plane flow casting and quality of amorphous ribbons for high Bs Fe-Co-Si-B-P-C alloy by the purification of melts

The presence of impurities and inclusions in raw materials represents a critical bottleneck in the industrial production of Fe-Si-B-C amorphous alloys, adversely affecting both the success rate of plane flow casting and the quality of the resulting ribbons. In this work, we elucidate the evolution of total oxygen content (T[O]) and characterize inclusions in the melt throughout the production process. By optimizing smelting and holding parameters, T[O] was maintained below 10 ppm at all stages. Inclusions-primarily oxides and complex silicates-exhibited spherical, triangular, or quadrilateral morphologies with sizes below 10 µm. Reducing inclusion density markedly enhanced plane castability, surface smoothness, lamination factor, and ductility. To achieve this, we developed a two-step purification approach combining argon bubbling via a dispersion gas-permeable brick with a zirconia-based foam-ceramic filter, lowering inclusion densities to below 200 inclusions mm⁻² and effectively preventing nozzle clogging. Finally, on a ten-million-ton-level production line, we produced Fe₈₀Co₃Si₁B₁₁P₄C₁ amorphous ribbons with defect-free surfaces and a saturation magnetic flux density (B_s) of 1.68 T These results demonstrate that rigorous inclusion control enables the industrial-scale manufacture of high-B_s Fe-Co-Si-B-P-C amorphous ribbons.