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Magnetic properties of Co-based amorphous ribbon under cyclic heating and cooling

Konieczny J., Borisjuk A., Pashechko M., Dobrzański L. A.

Journal of Achievements in Materials and Manufacturing Engineering

2010

Vol. 42, nr 1-2

42-49

Purpose: The aim of the work is to investigate the changes of magnetic properties of the cobalt based Co68Fe4Mo1Si13.5B13.5 alloy under cycling heating and cooling. Design/methodology/approach: The amorphous metallic ribbons were manufactured by planar-flow-casting method. Investigations of the magnetic properties were observed under permanent heating amorphous and partially crystallized alloy. Observations of the structure were made on the JOEL transmission electron microscope (TEM). Using the HFQS program the distributions of the magnetic hyperfine P(H) fields were determined for spectra smoothed in this way, employing the Hesse-Rübartsch method. Findings: The analysis of the magnetic properties under permanent heating and structure of the Co-based amorphous ribbons obtained in the by planar-flow-casting process proved that the permanent heating caused the crystallization of second magnetic phase after transition near to paramagnetic state. Research limitations/implications: The appropriate cyclic heating and cooling significantly decreasing soft magnetic properties of examined amorphous alloy. The cyclic heating beginning of elementary crystallization processes and the end of crystallization alloy. Practical implications: According to the results presented in the paper the examined Co-based glassy alloys as a soft ferromagnetic material may be utilized in construction of magnetic cores such as choke coils, common mode and noise filter and is of great technological interest. Originality/value: The paper presents influence of permanent heating on structural changes of metallic ribbons. Results and discussion of the influence of permanent heating on magnetic properties of metallic ribbon are presented.

Crystallization of Fe72B20Si4Nb4 metallic glasses ribbons

Nowosielski R., Babilas R., Griner S., Dercz G., Hanc A.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 34, nr 1

15-22

Purpose: The paper presents a crystallization process of Fe-based amorphous materials. The aim of work is presentation of the influence of annealing temperature on structural changes and magnetic properties of Fe72B20Si4Nb4 metallic glasses. Design/methodology/approach: The studies were performed on metallic glasses as ribbons. Crystallization behaviour of the studied alloy was examined by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Mössbauer spectroscopy methods. The soft magnetic properties examination of tested material contained magnetic permeability, coercive field, saturation induction and magnetic after-effects measurements. Findings: The XRD, TEM and Mössbauer spectroscopy investigations revealed that the studied alloy in as-cast state was amorphous. A two stage crystallization process was observed for studied material. The first stage of crystallization corresponding to the partial crystallization of .-Fe phase was followed by the formation of iron borides. It has shown that appropriate increasing of annealing temperature, significantly improved soft magnetic properties of examined alloy. The maximum of initial magnetic permeability is correlated with a minimum of coercive field. Practical implications: The soft magnetic properties of metallic glasses can be optimized by applying the appropriate conditions of heat treatment. Originality/value: The applied investigation methods are suitable to determine the changes of structure and the improvement of soft magnetic properties of examined Fe-based alloy in comparison with as-cast state.