Fig. 1 XRD patterns for melt-spin Fe81Si4B15 and Fe83Si4B13 alloys ribbons a, TEM images and corresponding selected area electron diffractions of b Fe81Si4B15, c Fe83Si4B13 alloys ribbons, respectively

Fig. 2 a Differential scanning calorimeter (DSC) curves for melt-spin Fe81Si4B15 and Fe83Si4B13 alloys ribbons with heating rate 5 K/min, b the Fe81Si4B15 alloy ribbons annealed at 708 K with magnetic fields 0, 6 and 12 T for 30 min with heating rate 20 K/min, respectively

Fig. 3 a XRD patterns for the Fe81Si4B15 alloy annealed at 708 and 728 K for 30 min with magnetic fields 0, 6 and 12 T, b Fe83Si4B13 alloy annealed at 683 and 703 K for 30 min with magnetic fields 0 and 12 T, respectively

Fig. 4 Bright-field TEM images for the Fe81Si4B15 ribbons annealed for 30 min with different temperatures and magnetic fields

Fig. 5 Bright-field TEM images of the Fe83Si4B13 alloys annealed at different temperatures and magnetic fields for 30 min

Fig. 6 Grain size distribution of α-Fe crystals precipitated in the Fe81Si4B15 alloys annealed at different temperatures and magnetic fields for 30 min

Fig. 7 Grain size distribution of α-Fe crystals precipitated in the Fe83Si4B13 alloys annealed at different temperatures and magnetic fields for 30 min

Fig. 8 a Average number of nucleate sites of α-Fe crystal (Nc), b saturation magnetic flux density (Bs), c coercivity (Hc) for Fe81Si4B15 alloy annealed at different temperatures and magnetic fields for 30 min

Fig. 9 a Average number of nucleate sites of α-Fe crystal (Nc), b saturation magnetic flux density (Bs), c coercivity (Hc) for Fe83Si4B13 alloy annealed at different temperatures and magnetic fields for 30 min

Fig. 10 Bright-field TEM images of the Fe83Si4B13 alloys annealed at 683 K with annealing time of 5 a, 15 b, 30 min c under 12 T magnetic field

Fig. 11 Average number of nucleate sites and grain size distribution of α-Fe crystals precipitated in the Fe81Si4B15 alloys annealed at 683 K with annealing time of 5 a, 15 b, 30 min c under 12 T magnetic field