dc Joule heating of amorphous metallic ribbons: Experimental aspects and model

Abstract

A dc technique of Joule heating has been developed with the purpose of developing unconventional crystallization products in amorphous metallic ribbons. The thermal effects of a continuous current flow on Fe40Ni40B20 and Fe80Si10B10 amorphous ribbon strips are examined. The evolution of the temperature in samples submitted to different values of electrical current is followed by measuring the variations in the electrical resistance of the ribbon strips. A model of sample heating is developed and shown to predict both the steady-state temperature of the ribbon strips and the law of approach to the steady state. A number of experimental data, obtained from multiple-thermocouple measurements, x-ray diffractometry, and differential scanning calorimetry, support the model’s assumptions. The effect of fluctuations in the room-temperature resistance is discussed. The temperature behavior of samples submitted to free cooling after a Joule-heating treatment is considered.