Nanocrystallization kinetics of amorphous Fe81B13.5Si3.5C2 magnetic ribbons

The kinetics of the nanocrystallization of amorphous Fe₈₁B_13.5Si_3.5C₂ ribbon is studied. The changes in the microstructures and magnetic properties of ribbons annealed at 425 and 495 °C for 0.5-10 h were investigated using an X-ray diffractometer (XRD), Mössbauer spectroscopy (MS), differential scanning calorimeter (DSC) and vibrating sample magnetometer (VSM). The changes in the surface morphology were observed by a changed atomic force microscope (AFM). The XRD patterns and the Mössbauer spectrums show the formation of nanocrystallites of α-Fe(Si), Fe-B, Fe₃C and Fe₃Si of different grain sizes when annealed at different temperatures. The nanocrystallization kinetics of the Fe₈₁B_13.5Si_3.5C₂ ribbon are described by an Avrami growth curve with an exponent values of 1.34 and 1.01 for the isothermal annealing at 425 and 495 °C, respectively. AFM topography pictures and surface image show that the density of the microstructure and the size of the grain increase as higher annealing temperatures are used.