Abstract
The work investigated the temperature dependences of the kinematic viscosity for multicomponent melts of nanocrystalline soft magnetic alloys. It is shown that there is a linear relationship between the reduced activation energy of viscous flow Ea·(RT)−1 and the pre-exponential factor ν0. This ratio is universal for all quantities, the temperature dependence of which is expressed by the Arrhenius equation. It is shown that the activation energy of a viscous flow is linearly related to the cluster size on a natural logarithmic scale, and the melt viscosity increases with decreasing cluster size. The change in the Arrhenius plot in the anomalous zone on the temperature dependence of viscosity can be interpreted as a liquid–liquid structure transition, which begins with the disintegration of clusters and ends with the formation of a new cluster structure.
Highlights
It is shown that the activation energy of a viscous flow is linearly related to the cluster size on a natural logarithmic scale, and the melt viscosity increases with decreasing cluster size
Nanocrystalline soft magnetic materials are used for the manufacture of magnetic systems for various electrical devices [1]
The kinematic viscosity at the melting point and the pre-exponential factor were calculated from the relations ηm = νm ρm иη0m = ν0m ρm
Summary
Nanocrystalline soft magnetic materials are used for the manufacture of magnetic systems for various electrical devices [1]. The first and most widely used material was the classical nanocrystalline Finemet alloy with the chemical composition Fe73.5 Cu1 Nb3 Si13.5 B9 [2]. To obtain special magnetic properties, the classical composition can be modified with various chemical elements Ni, Co, Mo, V, Cr and others. Nanocrystalline soft magnetic materials are multicomponent alloys. When melting a multicomponent alloy, a mushy zone is formed between the solidus and liquidus temperatures, in which the liquid and solid phases coexist. After transition to a liquid state, the melt inherits the short-range order, which is associated with a more stable solid phase. The structural component of the melt is clusters, the size of which depends on temperature [3]
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