Improving the soft magnetic properties of the Fe_73.5Si_13.5B₉Nb₃Cu₁ nanostructured ribbons by annealing in the hydrogen atmosphere

Abstract

The nanocrystallization stage was performed in a reductive hydrogen atmosphere to prevent surface oxidation and improve the soft magnetic properties of the amorphous, Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 alloy through annealing. Both the amorphous and nanocrystalline Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 ribbons were characterized by differential scanning calorimetry, transmission electron microscopy, X-ray diffraction, alternative gradient field magnetometry, and AC susceptometry techniques. To reduce the processing cost, commercially available industrial gas sources were used at the atmospheric pressure, instead of high purity inert gas or high vacuum ambient. The surface oxidation completely stopped after using a 70% Ar-30% H 2 mixture of such gases, also the period of the nanocrystallization stage decreased. Moreover, it was observed that the soft magnetic parameters of the nanocrystalline samples depend on the annealing time. Both the in-plane permeability and coercive field of the ribbons improved through nanocrystallization and the optimum annealing time was determined.