Magnetic properties in rapid current annealed Fe85.2Si0.5B9.5P4Cu0.8 (NANOMET) ribbon

Abstract

Nanocrystallization of an Fe85.2Si0.5B9.5P4Cu0.8 alloy was induced by two different types of heat treatments employing Joule heating technique. In one case, continuous pulses of increasing amplitude of annealing current are supplied on a single sample, while in the other case, constant increases of the annealing current are used on different samples. The results show that with the first type of experiment it is possible to study the structural evolution of the alloy, providing that the amplitude of the pulse remains less than a maximum value. With the second type of experiments we have obtained the maximum value of heating rate for our system to achieve the nanocrystallization of the magnetically soft phase and avoiding the precipitation of phases that deteriorate the magnetic properties. The soft magnetic properties obtained with the second type of heat treatment are similar to those obtained in the literature with other types of thermal treatments. The work also presents measurements of electrical resistance and dilatometry during the structural evolution of the studied alloy.