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Microstructure, thermal stability and magnetic properties of bulk amorphous Fe73-xCoxNb5Y3B19 (x = 0 or 10)

Marcin G. Nabiałek ,  Katarzyna Sobczyk ,  Józef Zbroszczyk ,  Jan Świerczek ,  Wanda Ciurzyńska ,  Jacek Olszewski ,  Joanna Gondro 

Institute of Physics, Częstochowa University of Technology, Al. Armii Krajowej 19, Częstochowa 42-200, Poland

Abstract

Iron-based bulk amorphous alloys are interesting for basic studies because they have promising magnetic properties for technical applications. These alloys usually contain more than three elements and show better thermal stability of magnetic properties than classical amorphous ribbons.

In this paper we present the influence of iron replacement by cobalt on the microstructure, thermal stability and magnetic properties of the bulk amorphous Fe73-xCoxNb5Y3B19.

Ingots of the alloys were prepared by arc melting of elements in a protective argon atmosphere. Plates 10 mm long with a cross section of about 0.5 mm x 10 mm were obtained by a rapid solidification of molten materials in a copper mold cooled with water (a suction casting method).

The amorphicity of the samples was tested by a X-ray diffractometer with Co Kα radiation and Mössbauer spectrometer.  These investigations were carried out at room temperature for the powdered samples. The thermal stability of the alloys was examined by differential scanning calorimetry (DSC). DSC curves were recorded at the heating rate of 10 K/min.  The Curie temperature was found from thermomagnetic curves obtained by a force magnetometer. The hysteresis loops and magnetization curves versus the strength of the magnetizing field were measured by a vibrating sample magnetometer.

The as-cast samples were fully amorphous. No traces of peaks originating from crystalline phases were seen in X-ray diffraction patterns and Mössbauer spectra consist of broad and overlapping lines characteristic of the amorphous state. In the DSC curves the pronounced peak at about 900 K corresponding to the primary crystallization is visible. The investigated alloys are soft magnetic materials exhibiting low coercivity and relatively large magnetic saturation polarization. The magnetization process at high magnetic field is connected with rotation of magnetic moments near the structural defects called quasi-dislocation dipoles. 

 

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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Katarzyna Sobczyk
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-06-10 09:41
Revised:   2009-06-10 22:39