Influence of annealing treatment on magnetic properties of submicron sized amorphous Fe–Co–B particles

This article reports the influence of annealing treatment on magnetic properties of submicron sized amorphous Fe–Co–B particles synthesized by an aqueous solution reduction method. The structure of Fe–Co–B particles was mainly amorphous for the annealing temperature less than 250 °C, a precipitation of bcc phase from the amorphous at the annealing temperature of 300 °C, and further transferred to the bcc structure at the annealing temperature above 350 °C. Their static magnetic properties such as saturation magnetization and coercivity were improved markedly at lower annealing temperatures, compared to those of as-synthesized particles, due to the enhancement of short-range order and the relaxation of internal stress. The imaginary part of complex permeability was maintained as almost zero in the frequency range of 0.3–0.5 GHz, meaning the suppression of eddy current. Therefore, these results suggest that the appropriate annealing treatment for submicron sized amorphous Fe–Co–B particles has considerable potential to develop the constituent materials of the next-generation magnetic elements.