Published in

IOP Publishing, Journal of Physics: Condensed Matter, 29(18), p. 6607-6620, 2006

DOI: 10.1088/0953-8984/18/29/004

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Evidence for new crystalline phases formed during early stages of crystallization of amorphous FeCuNbSiB alloys

Journal article published in 2006 by G. A. Basheed, S. Sarkar, S. N. Kaul
This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

Amorphous FeCuNbSiB alloys with composition near Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 (the well-studied FINEMET alloy) were annealed at 520 °C for different durations of time, t A , varying from 3 to 20 min. Detailed investigation of the structure and composition of crystalline phases formed during the initial stages of crystallization in these alloys using techniques such as x-ray diffraction, Mossbauer spectroscopy, scanning electron microscopy, atomic force microscopy and energy dispersive absorption of x-rays, revealed the following. New crystalline phases, tetragonal Fe 3 B and hexagonal Fe 2 Si, not reported previously, exist in all the nanocrystalline alloys in question in contrast to the well-documented cubic Fe-Si phase with the DO 3 structure which coexists with the Fe 3 B and Fe 2 Si phases in some compositions only. The crystallization of Fe 3 B and Fe 2 Si nanocrystalline grains starts at the surface of the ribbons and then proceeds to the bulk whereas the crystallization of DO 3 Fe-Si gets initiated within the bulk. The average size of the nanocrystalline grains of the Fe 3 B and Fe 2 Si and cubic DO 3 Fe-Si structures in the residual amorphous matrix is around 20 nm but their volume fractions are as low as ≈ 5%, 10%, and 7%, respectively. The cubic Fe-Si nanocrystals of the DO 3 structure have a silicon concentration in the range 15-20 at.%. The magnetic moments in the amorphous precursor point, on average, are 40° out of the ribbon plane while in the nanocrystalline alloys this angle varies between 2° and 19° depending on the Fe concentration.