Magnetic behavior of nanostructured glass covered metallic wires

We present a study of the evolution of the magnetic properties and behavior of Fe73.5CU1Nb3Si13.5B9 glass covered wires and wires after glass removal with the annealing temperature up to 600 degrees C starting from the amorphous state. The changes induced in the magnetic properties of these wires are determined by the stress relief process occurring at temperatures below 550 degrees C, and by the appearance of the nanosized alpha-FeSi crystalline grains after annealing for 1 h at 550 degrees C. The nanocrystalline phase formation leads to an improvement of the soft magnetic properties of these wires-increase of permeability and decrease of the coercive force-but also determines the disappearance of the large Barkhausen effect presented by these wires in the amorphous state. Annealing at temperatures over 550 degrees C determines a depreciation of the soft magnetic properties of both glass covered wires and wires after glass removal. The magnetic behavior of such wires can be fully explained by taking into account the relaxation of the internal stresses with increasing the annealing temperature as well as the changes in the magnetostriction constant due to the appearance of the nanocrystalline grains. (C) 1997 American Institute of Physics.