Achieving constant magnetic permeability in Fe-based nanocrystalline alloys by Ni alloying and magnetic-field annealing for high DC bias capability and low coercivity

Abstract

The influence of shape, orientation, and motion patterns of magnetic domains in nanocrystalline strips with a high Ni content on soft magnetic properties was studied using normal isothermal annealing and transverse magnetic field annealing (TFA). The results indicate that TFA-10 (with 10 at. % Ni) exhibits the lowest coercivity (Hc) at 0.33 A/m and a remanence ratio (Br/Bm) of 0.2%. Moreover, more stringent conditions for the anisotropy field (Hk) are applied, and the resistance to current bias is assessed by examining the relationship between the field-induced magnetic anisotropy (Ku) and the current magnitude. A highly linear hysteresis loop with an anisotropy field (Hk) of 210 A/m was achieved, resulting in an effective permeability (μe) of 5000 at 500 kHz and 0.5 V. Furthermore, the current required to maintain a 100% bias ratio is determined to be up to 12 A. This study demonstrates the excellent soft magnetic properties of TFA-10 and guides optimizing the constant permeability properties of nanocrystalline alloys.