Effect of tensile and torsion on GMI in amorphous wire

GMI effect, Delta Z/Z = [Z(H) - Z(H-max)]/Z(H-max) has been measured in (Fe0.94Co0.06)(72.5)B15Si12.5 wire under tensile, sigma(ten), and torsional, sigma(tor), stresses. Generally Delta Z/Z(H) dependence has a non-monotonic shape with a maximum at certain axial magnetic field, H-m. Both tension and torsion modify Delta Z/Z(H) dependence. Application of tension results in an increase of H-m with sigma(ten). Torsional stress dependence of GMI effect has asymmetry with a maximum at torsion angle, phi, around +12 pi/m in as-cast wire, when Delta Z/Z is around 250%. An increase of Delta Z/Z(m) up to 350% and change of Delta Z/Z(phi) dependence towards a nearly symmetric shape have been observed after Joule heating. (C) 1999 Elsevier Science B.V. All rights reserved.