COMPARATIVE STUDY ON MICROSTRUCTURE AND MAGNETIC PROPERTIES OF AMORPHOUS WIRES WITH DIFFERENT DIAMETERS

X-ray diffraction (XRD), Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and magnetic measurement system were used for investigating the microstructure and magnetic properties of melt-extracted Co_68.15Fe_4.35Si_12.25B_15.25 microwires with diameters of 52 μm and 83 μm for potential applications. Experimental results indicated that as-cast wire with 52 μm was entirely amorphous characteristic, while partial nano-crystalline structure including regularly atomic arrangement in microregions could be observed in 83 μm wire. There was a transform of increased coercivity and decreased magnetic permeability with an increasing diameter, resulting from the magnitudes of the magnetic anisotropy induced by the residual inner stress and magneto-crystalline anisotropy. It can therefore be concluded that the 52 μm wire has better magnetic properties, is more suitable for potential applications in magnetic field sensors.