Crystallization process, microstructure, thermal behavior, and magnetic properties of melt-spun Fe86Cr6P6C2 ribbons

The crystallization process, microstructure, thermal stability, and magnetic properties of Fe86Cr6P6C2 amorphous ribbons were studied by X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, differential scanning calorimetry, and vibration sample magnetometry. The crystallization process occurs in three stages where nanocrystalline alpha-Fe solid solution, Fe3P phosphide, theta-Fe3C and epsilon-Fe3C carbides are formed. The crystallite size increases with increasing annealing temperature and remains at the nanometer scale (20-88 nm). The microstructure of the annealed ribbons consists of lamella, fine platelets, alternate planes of ferrite and cementite, and grains with different shapes and sizes. The activation energies (499, 386, and 369 kJ/mol) are determined by Kissinger method. The melt-spun ribbons exhibit a low coercivity of 16.598 Oe and a high saturation magnetization of 0.635 emu compared to the annealed ones. The saturation magnetization decreases to a minimum value for the annealed ribbons at 758 K and then increases with increasing the annealing temperature. The Curie temperature increases from 447.4 K for the melt-spun ribbons to 638 K for the fully crystallized ribbons due to the development of the alpha-Fe phase.