D.C. magnetic properties of metallic glasses after flash annealing

In this study, flash annealing involves passing a well shaped d.c. current pulse of known duration, through a straight strip of metallic glass. The rapid temperature rise (∼ 5000 K s-1), the high final temperature (~500-600), the short pulse duration (112 ms), and the rapid cooling at the end of the pulse (∼500 K s-1) combine to achieve a thermal cycle unobtainable in a conventional furnace treatment. This study shows that a lower value of coercive field, Hc, can be achieved after flash annealing than is possible in a furnace treatment. The uniaxial anisotropy, Ku, is also reduced by flash annealing. A discussion of the results is given in terms of stress relief, creep enhanced relaxation and the total degree of relaxation attainable. A novel method of heat treating metallic glass cores is outlined, as an extension of this work.