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

The melt-spun Fe83.3-84.3Si4B8P3-4Cu0.7 alloys have a heterogeneous amorphous structure including a large amount of alpha-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 alpha-Fe grains with size of 10-17 nm in diameter can be realized from the heterogeneous amorphous alloys. The nanocrystallized Fe83.3-84.3Si4B8P3-4Cu0.7 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 A/m 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) X 10(-6). In addition, the nanocrystalline alloys exhibit the superior core loss to the representative Fe78Si9B13 amorphous alloy at 50 Hz. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3058624]