Soft magnetic Fe-based metallic glasses prepared by fluxing and water-quenching

[(Fe_0.5Co_0.5)_0.75B_0.20 Si_0.05]₉₆Nb₄ soft magnetic bulk metallic glasses were prepared by fluxing and water-quenching in a silica tube. Dimension of the bulk metallic glass specimens was up to 7.7 mm in diameter, which is about 1.5 times larger than those prepared by Cu mold-casting. The critical cooling rate of [(Fe_0.5 Co_0.5)_0.75B_0.20 Si_0.05]₉₆Nb₄ alloys with fluxing for forming a metallic glass phase was 150 - 170 K/s, which was considerably smaller than that without fluxing. Saturation magnetization was 1.13 T, and coercivity was lower than 20 A/m. Fluxing suppresses heterogeneous nucleation by isolating the nucleation sites from the molten alloys and improves their glass-forming ability.