Transformation kinetics of the Fe73.5Cu1Nb3Si13.5B9 ribbons to the nanocrystalline state

The transformation kinetics of the as-quenched Fe73.5Cu1NBb3Si13.5B9 ribbons to the nanocrystalline structure has been studied. A differential scanning calorimeter in the continuous-heating and isothermal measuring regimes and a thermobalance with a permanent magnet have been used. in differential scanning calorimetry (DSC) peak in the continuous-heating regime is wide and asymmetrical, having a long high temperature part and a small transformation enthalpy. The DSC signal in the isothermal regime is monotonically decreasing with a temperature-dependent amplitude, the total transformation enthalpy being slightly changed. Both as-quenched and nanocrystalline samples exhibit two magnetic transformations namely the glass-like and the nanophase-like transformations, the mutual proportion between them being changed with the proceeding transformation. e observed phenomena are interpreted by the grain growth mechanism of the coarsening of the already existing fine-crystalline structure to the nanocrystalline structure. The experimental results can be interpreted also by the Johnson—Mehl—Avrami nucleation-and-growth crystallization mechanism with an abnormal exponent n ≈ 0.9.