A NEW TECHNIQUE FOR DYNAMIC ANNEALING OF AMORPHOUS-ALLOYS USING JOULEEFFECT WITH CONTROLLED MECHANICAL TENSILE-STRESS

We present a new dynamic technique performed in air and under mechanic al stress, intended to anneal amorphous metallic ribbons on their fina l curvature. This method is based on dc Joule heating. The ribbon is r aised to high temperature for short time (a few tens of seconds) while it is subjected to a tensile stress. The maximum annealing temperatur e was measured by means of an infrared pyrometer which necessitates th e value of total emissivity of the heated ribbon. This emissivity was determined by using a simple experimental device. To illustrate the in terest of this new technique, we give, as an example, the magnetic pro perties obtained after dynamic annealing on Fe-based amorphous alloys with high magnetostriction (Fe78B13Si9). The experimental results show the influence of the different annealing parameters on the magnetic p roperties. This method has also been used successfully to anneal other amorphous alloys (e.g., Fe-Ni-based and Co-based alloys) and to obtai n nanocrystalline ribbons. (C) 1995 American Institute of Physics.