Devitrification process of FeSiBCuBbX nanocrystalline alloys: Mössbauer study of the intergranular phase

Abstract

Mössbauer experiments were performed at room temperature using different experimental configurations on several series of nanocrystalline FeSiBCuNbX alloys (X = Zr, Nb, Mo and V) obtained after annealing treatments of melt-spun ribbons. The refinement of Mössbauer spectra allows the kinetics and the local structural rearrangement mechanisms associated with the nanocrystallization process to be compared. The hyperfine field distributions of the intergranular phase show the emergence of a bimodal behaviour that becomes significantly more pronounced from volumetric crystalline fractions estimated at ∼20-25%, regardless of the nature of the substituting element. The hyperfine field distribution can be described by means of two Gaussian components, consistent with of a two-cluster-like model. Such a behaviour can be attributed to the presence of iron-rich and iron-poor zones within the intergranular phase, resulting from the diffusion process. These mechanisms are found to be independent of the nature of X. In addition, strong in-plane magnetic structures are evidenced for Nb-, Mo-, and V-based systems while the magnetic domains tend to be randomly distributed in Zr-based nanocrystalline alloys.

Structural and magnetic properties of the intergranular amorphous phase in FeNbB nanocrystalline alloys

“…In another respect the low field values suggest the existence of Nb-rich zones: these iron atoms have to be located in close contact with the Nb-rich shells created around the crystallites during the crystallization process. Such a situation was recently modelled during the devitrification of Finemet alloys [14]. Such features totally confirm the strong heterogeneity of the amorphous remainder.…”

Microstructural properties of (Fe, Co)SiBCuNb nanocrystalline alloys

“…In this paper the effect of partial replacement of Fe by Co on the nanocrystallization process of Fe 73.5−x Co x Si 13.5 B 9 Cu 1 Nb 3 (x = 13.5 and 60) alloys is studied by means of x-ray diffraction (XRD), Mössbauer spectrometry (MS) and thermomagnetic measurements (TMG). These results will be compared with those obtained previously on Co-free nanocrystalline alloys [7]. Study of the composition of the crystalline Fe, Co, Si grains requires the combination of Mössbauer and XRD data.…”

Mössbauer Spectroscopy Characterization of Soft Magnetic Nanocrystalline Alloys

“…This problem will be discussed in detail in the next section, devoted to NANOPERM-type alloys. Borrego et al (2000) studied several series of nanocrystalline FeSiBCuNbX alloys (X = Zr, Nb, Mo, V). By applying a refined fitting procedure (which basically resembles the models discussed above) the hyperfine field distributions were compared for various X atoms.…”