Soft Magnetic Fe–Zr–Si–B Alloys with Nanocrystalline Structure

Abstract

Good soft magnetic properties and high saturation magnetization (Bs) were obtained for the Fe₈₇Zr₇Si₄B₂ and Fe₈₆Zr₇Si₄B₃ alloys with the partially crystallized structure consisting of nanoscale bcc grains surrounded by the remaining amorphous phase. These alloys consist only of an amorphous phase and have good bending ductility in the as-quenched state and the partial crystallization to the nanocrystalline structure by annealing for 3.6 ks at 873 K causes the simultaneous achievement of 1.6 T for Bs, 14000 for permeability at 1 kHz (μe) and <1×10⁻⁶ for magnetostriction (λs). No zero magnetostriction is obtained for nanoscale bcc Fe₉₀Zr₁₀ and Fe₉₀Zr₇B₃ alloys and the addition of about 4 at% Si is essential for the achievement of the zero magnetostriction in the Fe–Zr base alloys. The glass formation at the new alloy compositions, the good ductility in the as-quenched amorphous state and the good soft magnetic properties in the partially crystallized state allow us to expect that the present alloys develop subsequently as a new type of soft magnetic material.