High-Frequency soft magnetic properties of Fe-Si-B-P-Mo-Cu amorphous and nanocrystalline alloys

This paper deals with formation, thermal stability and magnetic properties of Fe-Si-B-P-Mo amorphous and nanocrystalline alloys with minor Cu alloying. Amorphous melt-spun Fe84-85B8P3.5.4Mo1-2Cu0.5.1 (at%) alloy ribbons show good bending plasticity and crystallize through two stages with each onset temperature of about 673 and 813 K. Good soft magnetic properties were obtained in both amorphous and nanocrystalline (bcc-Fe + amorphous) states. The highest saturation magnetization and the lowest coercivity are similar to 1.4 T and similar to 4 A/m, respectively, for the amorphous phase and 1.8 T and 2.5 A/m, respectively, for the bcc-Fe + amorphous phases. The frequency dependence of permeability for nanocrystalline Fe84B8P3.5Si1.5Mo2Cu1 alloy remains nearly constant in a wide frequency range up to 65 kHz. Besides, the quality factor is higher over the whole frequency range up to 10 MHz for the nanocrystalline than for the amorphous alloy. These characteristics are promising for future engineering of high-frequency type soft magnetic materials.