Crystallization kinetics of amorphous Fe67Co9.5Nd3Dy0.5B20

The crystallization kinetics of amorphous Fe67Co9.5Nd3Dy0.5B20 was studied by differential scanning calorimetry in the mode of isochronal heating and isothermal annealing. In the case of isochronal heating, the crystallization peak temperature Tp shows a strong dependence on the heating rate. The activation energy for the crystallization (535 kJ/mol) was determined by the Kissinger method. The isothermal transformation kinetics was modeled by the Johnson-Mehl-Avrami (JMA) equation. The Avrami exponents are in the range of 4.30-4.75 suggesting that the isothermal crystallization is governed by three-dimensional growth with an increasing nucleation rate. The activation energy of the crystallization derived from the isothermal annealing experiments according to the Arrhenius relation was calculated to be 557 kJ/mol.