Crystallization progress and soft magnetic properties of Finemet alloy with Ge addition

The influence of the partial substitution of Si by Ge (6 at.%) on the structure, crystallization kinetics and magnetic properties of Finemet-type alloys were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) and room-temperature hysteresis loops measurements. Amorphous ribbons were heat treated at different temperatures for 1 h in a vacuum furnace to induce nanocrystallization. It was found that a homogeneous structure of alpha-Fe3Si structure nanocrystals with a grain size less than 15 nm embedded in an amorphous matrix was obtained within the temperature range of 510-590 degrees C. The crystallization activation energies calculated using Kissinger model were 331 and 356 kJ/mol for the first and the second crystallizations, respectively. The saturation magnetization of the as-quenched amorphous ribbon is 138 Am-2/kg and decreases gradually with the increase of annealing temperatures from 125 Am-2/kg for 510 degrees C to 115 Am-2/kg for 590 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.