The ordering process and magnetic structure of iron‐aluminium alloys near the composition Fe3Al are studied experimentally by the Mössbauer technique. It is found that the isomer shift shows a pronounced hysteresis in the temperature range 750 to 850 °C which indicates the first order character of the B2‐type ordering. The simultaneous appearance of the central (paramagnetic) and hyperfine lines in the temperature interval 640 to 500 °C shows that the Mössbauer spectrum is a superimposition of two spectra. These originate from Fe57 nuclei on two different sublattices; one of them is paramagnetic (A sublattice) and the other is magnetically ordered (D sublattice). The hyperfine field and the isomer shift of the hyperfine lines show a pronounced discontinuity at the temperature of the DO3‐type ordering. At this temperature it is found the intensity ratio of the outer to adjacent peak also suffers a sudden change. This indicates a ferromagnetic to antiferromagnetic transformation which is not contrary to existing theoretical ideas but as yet lacks direct experimental confirmation.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics