Comparative study on microstructure and magnetic properties of amorphous wires with different diameters

X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and a magnetic measurement system were used for investigating the microstructure and magnetic properties of melt extracted Co68.2Fe4.3B15Si12.5 microwires with diameters of 52 and 83 mm for potential applications. Experimental results indicated that the as cast 52 mm wire was entirely amorphous, whereas a partial nanocrystalline structure, including regularly atomic arrangement in microregions, could be observed in the 83 mm wire. There was a trend of increased coercivity and decreased magnetic permeability with increasing diameter, resulting from the magnitudes of the magnetic anisotropy induced by the residual inner stress and magnetocrystalline anisotropy. It can therefore be concluded that the 52 mm wire has better magnetic properties and is more suitable for potential applications in magnetic sensors.