Joule-heating effects in the amorphous ${\mathrm{Fe}}_{40}$${\mathrm{Ni}}_{40}$${\mathrm{B}}_{20}$ alloy

The effects of Joule heating on the amorphous ${\mathrm{Fe}}_{40}$ ${\mathrm{Ni}}_{40}$ ${\mathrm{B}}_{20}$ alloy are investigated by measuring the time behavior of the electrical resistance of ribbon strips during such a treatment. The structural transformations occurring in subsequent stages of the process are studied by means of x-ray-diffraction, differential-scanning-calorimetry, and magnetic-permeability measurements. A continuous evolution from a fully amorphous to a fully crystalline structure may be followed. The crystallization mechanisms observed in Joule-heated samples differ from the ones occurring under conventional heating conditions. The electrical resistance displays a bump in the course of Joule heating. A quantitative model relating such a bump to the extra heat released to the sample by fast crystallization is proposed and discussed.