Structural transformations of Fe81B13Si4C2 amorphous alloy induced by heating

► Structural transformation of Fe81B12Si4C2 alloy investigated by XRD and Moessbauer. ► Phase composition and crystallite size were determined. ► Established structural differences between fishy and shiny sides of the ribbons. ► α-Fe3Si was found on the shiny side after heat treatment at 200 °C. ► α-Fe3Si was found on the fishy side after heat treatment at 450 °C.