M?ssbauer study of incompletely alloyed nanocrystalline Fe100 ? x Al x prepared by high energy ball milling

摘要

Mechanically alloyed Fe100 ? x Al x powders, with 20≤ x ≤90, have been studied by X-ray diffraction and room temperature 57Fe M?ssbauer spectroscopy. The milling time was chosen such that complete alloying does not take place. For a fixed milling time of 10 h, the rate of alloying was seen to increase exponentially with increase in Fe content. M?ssbauer spectra of all the samples consist of a broad magnetic sextet and a quadrupole doublet. The isomer shifts and quadrupole splitting of the doublets are typical of Al-rich, Fe–Al alloys. The area under the quadrupole doublet is a maximum for x = 66. Analysis of the M?ssbauer spectra indicates the formation off- stoichiometric Fe3Al phase for x < 66, while the formation of Fe clusters is largely responsible for the magnetic hyperfine component in x ≥ 66 compositions.