Diameter Dependence of Magnetic Properties of Co-based Metal Fibers

Weiye Chen,Shuling Zhang,Guihong Geng

doi:10.1590/1980-5373-mr-2019-0041

Weiye Chen, Shuling Zhang + Show 1 more

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https://doi.org/10.1590/1980-5373-mr-2019-0041

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Abstract

Naked Co68.25Fe4.5Si12.25B15 metal fibers with diameter from 25 µm to 100 µm are produced by melt extraction method. Significant diameter dependence of magnetic properties is studied. Their microstructure and magnetic properties of hysteresis loops and giant magneto impedance (GMI) effect at frequencies from 0.1MHz to13MHz are investigated. The results show that the coercivity increases with the diameter of fibers and the GMI effect is best in fiber with a diameter of 35µm. It is found that the cooling rate of solidification decreases with the increase of fiber diameter. And fibers are amorphous with the diameter of 50µm and there are nanocrystallines in fibers with a diameter of 85µm. The grain boundary blocks the magnetization process which makes lower circular permeability, larger coercivity and lower field sensitivity of GMI effect. The original microstructure of Co-based fibers decides their magnetic properties. Therefore, material design is important to improve the GMI effect in magnetic field sensor making.

Highlights

IntroductionGiant magneto-impedance (GMI) effect is a large and sensitive change in electrical impedance with the external dc magnetic field applied in a magnetic conductor[1]
It is found that the Co-rich metallic fibers have good soft magnetic properties and excellent giant magneto impedance (GMI) effect[5]
Naked wires prepared by melt extraction method are different from the hard drawing or glass-covered wires because there is no tensile stress induced by hard drawing process or the covered glass must be taken into account

Summary

Introduction

Giant magneto-impedance (GMI) effect is a large and sensitive change in electrical impedance with the external dc magnetic field applied in a magnetic conductor[1]. H. Chirac et al studied the impedance response of Co68.18Fe4.32Si12.5B15 wires prepared by rotating water rapid quenching and found thinner wires had better GMI effect at low external field[6]. Chirac et al studied the impedance response of Co68.18Fe4.32Si12.5B15 wires prepared by rotating water rapid quenching and found thinner wires had better GMI effect at low external field[6] They found the reduction of diameter by cold drawing produced a significant increase in GMI response[6].

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