TEMPERATURE VS HEATING RATE TRANSFORMATION DIAGRAM FOR A TRANSITION FROM THE AMORPHOUS TO THE NANOCRYSTALLINE STATE

In this work, the transformation kinetics from the amorphous state to the nanocrystalline (NC) phases in an Ni-P alloy were investigated by means of differential scanning calorimetry (DSC) and a magnetothermal analysis (MTA) method. The temperature vs. heating rate transformation (THRT) diagrams for the amorphous-to-NC process, determined using the two experimental methods, are analysed comparatively. In the MTA meas urements, the transformation was found to start earlier than that in t he DSC measurement with the same heating rate. The transformation rang e in the THRT diagram determined from the MTA experiments is evidently wider than that from the DSC. The activation energies for the transfo rmation processes were calculated by means of the Kissinger equation. The activation energies for the initial crystallization at the sample surfaces were found to be smaller than those for the bulk crystallizat ion in both experiments. The difference between the results from the t wo different measurements was analysed according to the transformation thermodynamics and was attributed to the interface formation in the N C samples.