Structure and properties of melt-spun iron-silicon alloy filaments having single crystalline structure

Abstract

Melt-spun iron-silicon (Fe-Si) alloy filaments were obtained by a rapid solidification method using an in-rotating-water spinning apparatus. The silicon content in the alloy composition was selected to be about 6.5% by weight, which is expected to have no magnetostriction and to show the lowest coercive force in the magnetic field. Heat-treated filaments were also investigated in terms of the structure and the mechanical and magnetic properties. It was found that the cross-sectional areas and structures of as-spun filaments were affected by processing conditions, such as spinneret diameter, throughput, etc. In the case of the filaments with diameters less than about 90 μm, well-grown structures having primary dendrite arms oriented towards the direction of the filament length, can be observed in place of the polycrystalline structure. By means of high-temperature heat treatment, the filaments with the above structure were found to show single-crystalline structure without any clear boundary. The single-crystalline filaments were found to have good ductility to bending through 180 ° and excellent magnetic properties such as an almost perfect rectangular loop, low coercive force, and high saturation magnetic flux density in the d.c. magnetization curve.