Magnetoimpedance effect in the nanocrystalline Fe-Zr-Cu-B-Al alloy system

The magnetoimpedance (MI) of Fe92-x-yZr7BxCu1Aly (x=2,4,6,8,y=0,0.5,1,1.5) alloys has been measured to investigate the influence of the structural changes in the crystallization process as well as the changes of the soft magnetic properties such as permeability, magnetic anisotropy, etc. after thermal treatment. The MI measurements were carried out along the ribbon axis with longitudinal magnetic field. The nanocrystalline alloy system was prepared by the rapid quenching technique in an Ar atmosphere. Ultrasoft magnetic behavior has been observed in all samples annealed at 550 degrees C. The x-ray diffraction and transmission electron microscopy results show the alpha-Fe phase appeared in the annealed alloy system at 550 degrees C. The maximum magnetoimpedance ratio value in Fe84Zr7B3Cu1 alloy annealed at 550 degrees C was reached as much as 1100%. The field annealing does not contribute to improve the magnetoimpedance effect in these nanocrystalline alloy system. (C) 2000 American Institute of Physics. [S0021-8979(00)90608-X].