Magnetic properties and nanocrystallization process in Co-(Me)-Si-B amorphous ribbons

Magnetic properties of amorphous Co70Fe3Mn3.5Mo1.5Si11B11 and Co73Fe1Mn3Mo1Si13B9 alloys, manufactured in the form of ribbons by rapid cooling from the melt, were studied using vibrating sample magnetometer and thermo-magnetic methods. The Curie point (648 K and 683 K), coercive force (180 A/m and 40 A/m), and saturation magnetization (83 Am-2/kg and 85 Am-2/kg) were defined. The nanocrystallization process of the amorphous Co70Fe3Mo1.5Mn3.5Si11B11 and Co73Fe1Mo1Mn3Si13B9 alloys were studied by DTA, X-ray diffraction, and using the thermo-magnetic method in the high magnetic field 800 kA/m. The crystallization onset temperatures of the alloys were defined as about 787 K and 729 K, respectively. The effect of a magnetic field on the crystallization behavior, revealed in a notable crystallization onset temperature decrease, was observed. The structure evolution induced by the isothermal annealing at temperature 753 K was studied and the X-ray diffraction structure analyses revealed nanocrystallization with hcp-Co, fcc-Co, and Co3B phases. FESEM studies revealed a nanoscale and flower-like structure on the ribbon surface after annealing at 753 K.