Influence of microstructural inhomogeneity of individual sides of Fe81Si4B13C2 amorphous alloy ribbon on thermally induced structural transformations

As a result of the preparation process of Fe81Si4B13C2 amorphous alloy ribbon, a difference has been observed between the opposite sides of the ribbon in microstructure and surface morphology. Influence of these differences on thermally induced structural transformations was studied. Thermal treatment below 600 °C had a significant influence on the evolution of the microstructure, as well as phase composition of individual sides of the ribbon. Treatment at higher temperatures caused the microstructural differences between two sides to decrease significantly. Phase composition of the alloy samples showed the opposite trend: the differences observed were the greatest in the fully crystallized alloy, after treatment at 700 °C. These differences are the result of different numbers of nucleation sites for Fe2B phase on respective sides of the ribbon, leading to 30% difference in its content on different sides in the fully crystallized alloy.