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Partially devitrified metallic glasses

Lachowicz H. K., Zaveta K., Ślawska-Waniewska A.

Journal of Technical Physics

2002

Vol. 43, no 4

527-542

The paper presents a review of selected experiments which have been carried out using partially devitrified Fe- and Co-based metallic glasses as the research objects. It is shown that by a suitable choice of the composition of the metallic glass and also by the conditions of annealing, a variety of magnetic phases can be created in these systems. It is also shown that by controlled processes of annealing, the coercivity of metallic glass can be altered by several orders of magnitude, giving a possibility to produce materials with the extremely soft magnetic properties, up to the magnetically semi-hard ones. The magnetostriction of nanocrystalline materials of the FINEMET-type is discussed as well, showing that the size-dependent phenomena and the symmetry restriction at the particle boundaries create the surface contribution to the effective magnetostriction. Finally, the magnetic interactions between particles in partially devitrified samples are considered and the observed effects of temperature and hydrostatic pressure discussed.

Fe-N system: α"-Fe₁₆N₂- giant moment or not?

Zaveta K.

Electron Technology

1998

Vol. 31, No. 1

97-100

In the present work we studied the Mossbauer spectra (MS) in order obtain additional information about the phase composition of the samples from the Fe-N system. Beside the desired α"Fe₁₆N₂, the presence of the following phases were indicated: αFe, γFeNx, α'FeNx and γ'Fe₄N. The ⁵⁷FeMS were obtained at 300 K from our powdered samples in the transmission mode with the ⁵⁷Co in Cr matrix as the source. The spectra were fitted with up to 6 sextets, a doublet and a singlet attributale to the mentioned phases. Thier amount was estimated from the relative intergral areas of the respective lines. The average magnetic moments of the present Fe atoms were derived from the corresponding huperfine fields under the assumption of a linear relation between the field and the local moment. They were found to be reasonably correlated with the moments determined from the direct magnetic measurements. The results indicate that at least in one site of the α''Fe₁₆N₂ phase the local moment of Fe is considerably increased with respect to α iron.