Enhancement of glass-forming ability of CoFeBSiNb bulk glassy alloys with excellent soft-magnetic properties and superhigh strength

Co-based bulk glassy alloys with diameters up to 4.5 mm were formed in Co46Fe20B22+xSi6−xNb6 (x = 0–2) system. The increase of B to Si concentration ratio is effective in improving the glass-forming ability. In addition to high glass-forming ability, the glassy alloys exhibit excellent soft-magnetic properties, i.e., high saturation magnetization of 0.63–0.69 T, low coercive force of 1.17–2.35 A/m, and high effective permeability of 1.36–2.65 × 104 at 1 kHz under a field of 1 A/m. The bulk glassy alloys also exhibit superhigh fracture strength of 4400 MPa.