Structure, microstructure and hyperfine properties of nanostructured FeAl and FeAl–2wt%Sn powders

Abstract

Fe–Al and Fe–Al–Sn alloys were prepared using the high-energy ball milling process. The effects of adding small amounts of tin on structural and microstructural properties were studied using X-ray diffraction (XRD), ⁵⁷Fe Mössbauer spectroscopy, and scanning electron microscopy. The Mössbauer spectra of all samples reveal the presence of both magnetic and paramagnetic components. For Fe–Al alloys, the spectrum obtained after 1 h of milling contains a magnetically split sextet with a hyperfine field (Hₕ_f) of 33.1 T and an isomer shift (IS) of 0.00 mm/s, characteristic of the starting bcc Fe powder. The spectrum recorded after 32 h of milling indicates more advanced alloying. At this stage, a significant decrease in the intensity of the bcc Fe sextet in favor of the paramagnetic quadrupole doublet’s intensity was observed. The doublet seen in the center of the Mössbauer spectrum was attributed to the paramagnetic Fe(Al) solid solution. The relative fraction of this paramagnetic component increased to approximately 63.11%, with an isomer shift (IS) of 0.21 mm/s. For the Fe–Al–Sn alloy, the relative fraction of the paramagnetic component was found to be 33.33%.