Magnetic Properties of Fe_74.5−xCu_xTa₃Si_13.5B₉ As-Quenched Ribbons

Abstract

Fe_74.5−xCu_xTa₃Si_13.5B₉ nanocrystalline ribbons with appropriate Cu contents can be prepared without annealing processes. The Fe_74.5−xCu_xTa₃Si_13.5B₉ as-quenched ribbons with lower Cu contents (x≤1.5) consist of amorphous structure. The nucleation of α-Fe(Si) enhances with the increase of Cu content. An optimal Cu addition for obtaining the largest permeability, smallest saturation magnetostriction and largest magnetoimpedance occurs at x≈3. For as-quenched ribbons with high Cu contents (x≥3.5), soft magnetic properties deteriorate due to the drop of nucleation of α-Fe(Si) and the precipitation of Fe-B phases. For as melt-spun Fe_71.5Cu₃Ta₃Si_13.5B₉ (x=3) nanocrystalline ribbon prepared with wheel speed of 40 ms⁻¹, the average grain-size of α-Fe(Si) is about 10.5 nm, the initial permeability μ′ is about 35000, the saturation magnetostriction λ_s is less than 1×10⁻⁶, and the maximum value of magnetoimpedance ΔZ⁄Z₀ under a field of 7162 A/m is −12.88% at 2 MHz.