Comparison of Magnetostatic and Magnetoimpedance Properties for Amorphous Ribbons, Wires and Glass-Coated Microwires

Abstract

The physical properties of the amorphous metallic alloys are useful for different practical applications. For example, corrosion resistance of amorphous Fe-based alloys with reduced Cr content is higher than corrosion resistance of the crystalline stainless steel. An electric resistivity of amorphous phase is 2–4 times higher than of crystalline one usually, as a result, the lower eddy current losses can be detected. Ferromagnetic amorphous metallic alloys are extremely soft. More other, amorphous alloys have good mechanical properties and they can be manufactured in different forms: ribbons, wires, powder, microwires etc. As a result of these properties combination, ferromagnetic amorphous metallic alloys are widely used as high-frequency cores of transformers, high performed sensors etc. [1]–[3] There is the stress distribution through the characteristic size (diameter or thickness) because of rapid cooling manufacturing processes, whose influence on magnetic properties has drastic role. Depending on fabrication technique, the value of stresses and the distribution are various even for the same composition of the alloy. In our research we compared properties of amorphous ribbons (up to 2 cm width and 29 micron thickness), rapid quenching method – microwires (up to 180 micron in diameter), Ulitovski-Taylor technique – glass-coated microwires (up to 23 micron of metallic diameter and 29 micron of total diameter) with similar composition. Amorphous structure and chemical composition were examined by XRD and EDX analysis, correspondingly. Magnetostatic properties were studied by Vibrating Sample Magnetometer (VSM), high frequency magnetic properties – by spectrum analyser. For hysteresis loops measurements by VSM the 15 mm length of the samples and magnetic field amplitude up to 2kOe were used. For magnetoimpedace measurements the following characteristics were used: I AC till 20 mA, f AC = 0.5 −20 MHz, H ext = 0 −40 Oe. The comparison was made after length normalization. Depending on the stress distribution through the characteristic size of sample, its magnetic properties are quite different, shape of the hysteresis loops are drastic changed (see Fig. 1). Magnetoimpedance measurements allowed us, solving the inverse problem, to find the field dependences of the magnetic permeability of microwires with different diameters (see Fig. 2). Based the comparison we estimated the distribution of the permeability in the samples. Acknowledgement. The work was supported by the Russian Foundation for Basic research (grant No 18–02-00137)