Nanocrystallization kinetics of amorphous Fe73.5Cu1Nb3−xMoxSi13.5B9 (x=1, 2, 3) alloys

Amorphous ribbons of the alloy Fe73.5Cu1Nb3−xMoxSi13.5B9 (x=1, 2, 3) were prepared by the standard single copper wheel melt spinning technique in air atmosphere. The isothermal annealing was carried out at 550, 570 and 590 °C for 1 h in a vacuum furnace to study the effect of annealing temperature on the formation of nanocrystallite in as-spun ribbons. The X-ray diffraction (XRD) technique was used to analyse the grain size of the crystalline phase in the annealed samples. It was found that for samples annealed at 590 °C for 1 h, the average grain size increased from 13 nm for the sample with x=1 to 16 nm for the sample with x=3. The primary crystallization kinetics of amorphous ribbons was analyzed by non-isothermal differential scanning calorimetry (DSC) measurements. The crystallization activation energies of amorphous ribbons calculated by using Kissinger model were 347, 297 and 326 kJ/mol for x=1, 2 and 3, respectively. The calculated Avrami exponents n were 1.95, 2.14 and 2.00 for x=1, 2 and 3, respectively. The crystallization mechanism for the non-isothermal primary crystallization of the amorphous ribbons was discussed.