New Fe-metalloids based nanocrystalline alloys with high Bs of 1.9 T and excellent magnetic softness

The melt-spun Fe83.3-84.3 Si4 B8 P3-4 Cu0.7 alloys have a heterogeneous amorphous structure including a large amount of α-Fe -like clusters. Compared with the FeSiB alloys, the particle size rapidly decreases from several hundred nanometers to 2-3 nm due to the proper amounts of simultaneous P and Cu additions. By controlling the crystallization process, a homogeneous nanocrystalline structure composed by small α-Fe grains with size of 10-17 nm in diameter can be realized from the heterogeneous amorphous alloys. The nanocrystallized Fe83.3-84.3 Si4 B8 P3-4 Cu0.7 alloys show the extremely high saturation magnetic flux density of 1.88-1.94 T sufficiently near to 1.97 T of Fe-3.5 mass %Si crystalline soft magnetic alloys, and exhibit low coercivity of less than 10 Am and higher effective permeability of 16 000-25 000 at 1 kHz due to the simultaneous realization of the homogeneous nanocrystalline structure and the small magnetostriction of (2-3) × 10-6. In addition, the nanocrystalline alloys exhibit the superior core loss to the representative Fe78 Si9 B13 amorphous alloy at 50 Hz.