Magnetic annealing of zero magnetostrictive amorphous alloy with high saturation induction

Two different kinds of magnetic annealing were made for zero magnetostrictive amorphous Fe-Co-Si-B alloy with high saturation induction (10.1 kG). In a case of conventional magnetic annealing dc coercive force decreases to 12 mOe and maximum permeability increases as much as 8 × 10⁵. But initial permeability at 1 kHz decreases to 500. Because of induced magnetic uniaxial anisotropy, magnetization can reverse easily by 180° wall motion in dc field, but in ac field magnetization reversal through 180° wall motion increases eddy-current loss and initial permeability decreases. In order to improve permeability in the ac field without inducing anisotropy, another kind of magnetic annealing was performed. The samples were rotated in a dc field and were annealed. We first got high initial ac permeability alloy with high saturation induction for the type. Initial ac μ at 1 kHz, coercive force, and remanence are 12000, 13 mOe, and 5.8 kG, respectively.