Effect of Co Substitution and Thermo-Magnetic Treatment on the Structure and Induced Magnetic Anisotropy of Fe84.5-xCoxNb5B8.5P2 Nanocrystalline Alloys.

Aleksandra Kolano-Burian,Patryk Wlodarczyk,Anna Wojcik,Przemyslaw Zackiewicz,Maciej Szlezynger,Maciej Kowalczyk,Agnieszka Grabias,Wojciech Maziarz,Lukasz Hawelek

doi:10.3390/ma14123433

Abstract

In the present work, we investigated in detail the thermal/crystallization behavior and magnetic properties of materials with Fe84.5-xCoxNb5B8.5P2 (x = 0, 5, 10, 15 and 20 at.%) composition. The amorphous ribbons were manufactured on a semi-industrial scale by the melt-spinning technique. The subsequent nanocrystallization processes were carried out under different conditions (with/without magnetic field). The comprehensive studies have been carried out using differential scanning calorimetry, X-ray diffractometry, transmission electron microscopy, hysteresis loop analyses, vibrating sample magnetometry and Mössbauer spectroscopy. Moreover, the frequency (up to 300 kHz) dependence of power losses and permeability at a magnetic induction up to 0.9 T was investigated. On the basis of some of the results obtained, we calculated the values of the activation energies and the induced magnetic anisotropies. The X-ray diffraction results confirm the surface crystallization effect previously observed for phosphorous-containing alloys. The in situ microscopic observations of crystallization describe this process in detail in accordance with the calorimetry results. Furthermore, the effect of Co content on the phase composition and the influence of annealing in an external magnetic field on magnetic properties, including the orientation of the magnetic spins, have been studied using various magnetic techniques. Finally, nanocrystalline Fe64.5Co20Nb5B8.5P2 cores were prepared after transverse thermo-magnetic heat treatment and installed in industrially available portable heating equipment.

Highlights

This study aimed to determine the correlation between the conditions of thermomagnetic treatment of Fe84.5-x Cox Nb5 B8.5 P2 (x = 0, 5, 10, 15 and 20 at.%) nanocrystalline alloys with the induced transverse anisotropy and magnetic parameters such as core losses Ps, coercivity Hc and the magnetic permeability μ from the point of view of their possible applications in the area of induction heating
Order to scanning analyze the crystallization ropermcobalt alloys content with different cobalt ratios, In differential calorimetry (DSC) phenomenon measin Pyroperm alloys with different cobalt ratios, differential scanning calorimetry (DSC)
Detailed studies of Fe84.5 −x Cox Nb5 B8.5 P2 (x = 0–20 at.%) materials concerning the course of the crystallization process and the influence of the presence of a transverse magnetic field during annealing led to the determination of the optimal conditions for heat treatment (525 ◦ C for 20 min in the presence of a 140 kA/m transverse magnetic field) in order to obtain the maximum value of induced magnetic anisotropy while maintaining a high value of saturation magnetization

Summary

Introduction

The global trend of miniaturization and mobility is limited by the development of new efficient materials such as amorphous and nanocrystalline soft magnetic materials. These materials play an increasingly important role in the broadly understood area of energy conversion. One of the most important areas of development is the search for relatively cheap and easy-to-produce materials with the highest possible magnetic saturation. These materials, due to their excellent soft magnetic properties, such as high magnetic induction

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