S. Mirzaei , A. Jazayeri Gharehbagh,
Volume 31, Issue 1 (6-2012)
Abstract
The soft magnetic nanocrystalline Fe73.5Si13.5B9Cu1Nb3 alloy (FINEMET®) is produced by heat treatment of amorphous precursor. Determining kinetic parameters of amorphous structure transformation to nanocrystalline allows the control of microstructure (e.g. size and volume fraction of nanocrystalline grains) in order to achieve desired soft magnetic properties by optimizing the heat treatment conditions. In this research, the nanocrystallization kinetics of amorphous FINEMET alloy were studied using isoconversional and isokinetic methods under non-isothermal conditions of various heating rates ranging from 5 to 20˚C/min. The changes in the microstructure and magnetic properties of amorphous ribbon during nanocrystallization process were studied using X-ray diffractometry and hysteresisgraph, respectively.
S. Ahmadi, R. Arabi Jeshvaghani, H.r. Shahverdi,
Volume 34, Issue 1 (5-2015)
Abstract
In this research, crystallization of Fe36Cr12Mo10 and α-Fe phases in devitrification of Fe51Cr18Mo7B16C4Nb4 amorphous alloy was studied using X-ray diffraction and transmission electron microscopy. For evaluation of crystallization kinetics, differential scanning calorimetric tests were carried out at different heating rates. Results showed that two-step crystallization led to the formation of Fe36Cr12Mo10 and α-Fe phases in the structure of alloy. Activation energy of crystallization of Fe36Cr12Mo10 and α-Fe phases measured according to Kissinger-Starink model were 747 and 880 kJ/mol, respectively. Results growth mechanism along with the decreasing nucleation rate in crystallization of Fe36Cr12Mo10 and α-Fe phases.
