Radial distribution of magnetic permeability in amorphous CoFeNbSiB wires

The paper presents the results of the estimation of the radial distribution of magnetic permeability in amorphous Co$_{66}$Fe$_4$Nb$_{2.5}$Si$_{12.5}$B$_{15}$ wires by magnetoimpedance tomography. It was found that the radial distribution of the magnetic permeability is significantly non-uniform. In this case, the magnetic permeability takes a minimum value close to unity near the wire axis, and maximum values of several thousand in the middle part of the wire cross- section. It is shown that the magnetic permeability is largely determined by the magnitude and ratio of internal quenching stresses components in the deep regions of the wire. In the surface region of the wire, the value of the magnetic permeability can be significantly influenced by demagnetizing fields arising from inhomogeneities in the surface relief.