New Fe-Co-Ni-Zr-B amorphous alloys with wide supercooled liquid regions and good soft magnetic properties

New Fe-based amorphous alloys in Fe-Co-Ni-Zr-B system exhibiting a wide supercooled liquid region before crystallization and good soft magnetic properties were found to be formed by melt spinning. The composition range of the amorphous (Fe_1-x-yCo_xNi_y)₇₀Zr ₁₀B₂₀ alloys with the wide supercooled liquid region above 50 K extends from 0 to 36 at%Co and 0 to 30%Ni and the largest value of the supercooled liquid region defined by the difference between the glass transition temperature (T_g) and crystallization temperature (T_x), ΔT_x(= T_x-T_g) is 68 K for Fe₅₆Co₇Ni₇Zr₁₀B₂₀. The crystallization from the supercooled liquid of the Fe₅₆Co₇Ni₇Zr₁₀B₂₀ alloy upon continuous heating occurs through a single stage and the resulting crystallized structure consists of α-Fe, Fe₂Zr and Fe₃B phases containing Co and Ni elements. These Fe-based amorphous alloys exhibit good soft magnetic properties and the saturation magnetization, coercive force, permeability at 1 kHz and Curie temperature are respectively 0.96 T, 2.41 A/m, 17700 and 567 K for the amorphous Fe₅₆Co₇Ni₇Zr₁₀B₂₀ alloy annealed for 600 s at 750 K. The finding of the Fe-based amorphous alloys with good soft magnetic properties and high thermal stability of the supercooled liquid is important for future development of ferromagnetic bulk amorphous alloys.