Evolution of magnetic properties of amorphous Fe$_{78}$Si$_{13}$B$_9$ alloy during deformation and subsequent heat treatment

The structure and properties of the amorphous Fe$_{78}$Si$_{13}$B$_9$ alloy were studied after severe plastic deformation and subsequent heat treatment. The deformation was performed by torsion under high pressure at room temperature. The heat treatment was carried out at temperatures lower than the alloy crystallization temperature. The investigations were performed using X-ray diffraction, transmission electron microscopy, and vibrating-sample magnetometry. It was shown that the minimum coercive force (1.7 Oe) corresponds to the initial state and increases up to 2.6 Oe with an increase in the degree of deformation. It was found that the heat treatment of the deformed Fe$_{78}$Si$_{13}$B$_9$ alloy improves its soft magnetic characteristics. The successive annealings for 1 h and, then, 2 h at a temperature of 200$^\circ$C led to a decrease in the coercive force of the samples from 2.6 to 2.0 Oe.