Crystallization kinetics and magnetic properties of Fe63.5Co10Si13.5B9Cu1Nb3 nanocrystalline powder cores

Abstract Amorphous ribbons of the alloy Fe 63.5 Co 10 Si 13.5 B 9 Cu 1 Nb 3 were prepared by the standard single copper wheel melt spinning technique in air and their crystallization kinetics was analyzed by non-isothermal differential scanning calorimetry (DSC) measurements. The crystallization activation energies ( E x , E a 1 and E a 2 ) of amorphous ribbons calculated from Kissinger model were 448, 385 and 396 kJ/mol for the first and the second crystallizations, respectively. The Avrami exponent n was calculated from the Johnson–Mehl–Avrami (JMA) equation and was used to identify the crystallization mechanism for the amorphous ribbons. The ribbons were milled into different sized flakes, which were molded subsequently to cores using 3 wt.% epoxy as a binder. The effective permeability of the cores showed high frequency stability and increased with the size of the flakes. For the cores made from small sized flakes (− 75 μm), the quality factor was increased at high frequencies, which was attributed to the reduction in the eddy current loss.