Temperature distribution in dc Joule-heated amorphous ribbons

The model presented here allows us to find the temperature distribution in an amorphous ribbon through which a dc current passes. With this end in view, we have taken into account the most important dc Joule heating effects: conduction, convection and radiative heat losses as well as the structural changes that appear in the crystallization process. In the domain situated above the temperature that corresponds to the onset of the crystallization process, we have studied the thermal behavior of the sample and we have analyzed the kinetics of the crystallization phenomenon for both the isothermal process and for the nonisothermal crystallization process (based on the Johnson–Mehl–Avrami equation). The computed temperature values (corresponding to amorphous phase) are experimentally verified through magnetic measurements using a fluxmeter method (performed on amorphous ribbons with known Curie temperature), while those corresponding to the crystallization process are experimentally verified using differential scanning calorimetry analysis and X-ray difraction. We conclude that the dc Joule heating of ribbon is accurately described by this model, the analytically and numerically obtained results being in good agreement with experimental data. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)