Nanogranular Phase Formation During Devitrification of Fe(NiCo)ZrB Amorphous Alloys

Authors: B. Idzikowski¹; A. Szajek²

Source: Czechoslovak Journal of Physics, Volume 54, Supplement 1, December 2004 , pp. 59-66(8)

Publisher: Springer

Abstract:

A comprehensive review of our recent experimental and theoretical developments in the processing of nanocrystalline soft magnetic materials made by crystallization of amorphous precursors and containing new nanocrystalline phases is given. The relationship between the structures of the metastable and equilibrium phases and their transformations are discussed. Nickel-rich amorphous precursors with stoichiometry Ni₆₄Fe₁₆Zr₇B₁₂Au₁ were produced by melt-spinning technique and then heat-treated at temperatures ranged from 420 °C to 600 °C for one hour to form nanostructured alloy. The transformation from the amorphous state into the nanocrystalline state was investigated by the differential scanning calorimetry (DSC), the x-ray diffraction (XRD), the vibrating sample magnetometry (VSM) and Mössbauer techniques. The annealing favours the emergence of cubic Fe_xNi_23-xB₆ crystalline grains (10-25 nm in diameter). Magnetic measurements made at 4.2-1100 K reveal rather high value of saturation magnetization (nearly 60 and 40 Am²/kg at 4.2 K and room temperature, respectively) in amorphous as well as in nanocrystalline states. These facts are consistent with 300 K ⁵⁷Fe Mössbauer results which are well supported by the calculations of Ni and Fe magnetic moments in Ni₂₃B₆ and Fe₂₃B₆ phases, using the spin polarized tight binding linear muffin-tin orbital (TB-LMTO) method. However, anomalous high magnetic moments of Fe and Co atoms were found in some inequivalent positions in the crystal structure.

Keywords: nanocrystalline alloys; crystallization processes; electronic density of states

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10582-004-0031-5

Affiliations: 1: Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 61-179 Pozna, Poland , Email: idzi@ifmpan.poznan.pl , Poland , Email: idzi@ifmpan.poznan.pl "> 2: Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 61-179 Pozna, Poland,, Poland,">

Publication date: 2004-12-01

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