EFFECT OF THE QUENCHING RATE ON THE MAGNETIC-PERMEABILITY OF ANNEALED NON-MAGNETOSTRICTIVE CO-FE-MN-MO-SI-B GLASS

The dependence of the initial magnetic permeability and its stability during aging on the quenching ability of a quenchant (brine, water, oil and air) applied after annealing (708 K/10 min) of non-magnetostrictive Co71.5Fe2.5Mn2Mo1Si9B14 glass characterized by a medium value of T(c) was studied. It was found that the heat treatment enhances magnetic permeability mu-0.4 of the studied glass by a factor of 4-13 depending on the quenching medium. The highest value of mu-0.4 (> 25000) was obtained for the glass quenched with an intermediate quenching rate achieved in oil. An approximately linear decrease in mu-0.4 with the logarithm of aging time t of the studied glass was observed in as-quenched state as well as after heat treatment. The highest stability of mu was found for the glass annealed and slowly cooled in open air. The obtained results are explained on the basis of changes of local magnetic anisotropy during annealing and aging.