Correlation of Crystalline Structure with Magnetic and Transport Properties of Glass-Coated Microwires

Abstract

Abstract:We overviewed the correlation between the structure, magnetic and transport properties of magnetic microwires prepared by the Taylor-Ulitovsky method involving rapid quenching from the melt and drawing of the composite (metallic core, glass coated) wire. We showed that this method can be useful for the preparation of different families of magnetic microwires: soft magnetic microwires displaying Giant magnetoimpedance (GMI) effect, semi-hard magnetic microwires, microwires with granular structure exhibiting Giant Magnetoresistance (GMR) effect and Heusler-type microwires. Magnetic and transport properties of magnetic microwires depend on the chemical composition of metallic nucleus and on the structural features (grain size, precipitating phases) of prepared microwires. In all families of crystalline microwires, their structure, magnetic and transport properties are affected by internal stresses induced by the glass coating, depending on the quenching rate. Therefore, properties of glass-coated microwires are considerably different from conventional bulk crystalline alloys.

Technology, Preparation and Properties of the Cast Glass-Coated Magnetic Microwires

“…The expression: Dependence provided in Figure 5 is similar to that reported by the other authors (see [11][12][13][14][15][16][17][18]). The compositions that we have used are characterized by a high thermal stability; i.e., by a sufficiently high T cr -value.…”

“…Residual stresses relaxation by annealing can produce irreversible changes of magnetic properties (i.e., coercive field, Hc) allowing optimization of magnetic properties of microwires. At temperatures above 400 °C, the formations of a nano-or microcrystalline phases in CGCFMWs were observed (this temperature is designated as Tcr) [11][12][13][14][15][16][17]. Figure 5 shows a typical dependence of the coercive field on annealing temperature reflecting the relaxation of the residual stresses and first stages of the crystallization processes.…”

“…Properties of alloys at the nanoscale depend on the composition, size of constituting nanocrystals, as well as on their distribution within the amorphous phase [11][12][13][14][15][16][17]. Microwires with hard magnetic properties can be obtained by suitable thermal treatments (see Figure 6).…”

“…Figure 5 shows a typical dependence of the coercive field on annealing temperature reflecting the relaxation of the residual stresses and first stages of the crystallization processes. It is worth noting that in some compositions of magnetic microwires the heat treatment at temperatures below T cr can improve the CGCFMWs magnetic properties, i.e., decrease the values of σ H and H c [14][15][16].…”

“…Regardless of the application, in designing inductive components, the use of nanocrystalline cores typically provides the following advantages [11][12][13][14][15][16][17][18][19][20] At low temperatures, the value of exp{ −G/kT} is small (as-compared to a unity); therefore, formula:…”