A Mössbauer spectroscopy and neutron diffraction study of magnetostrictive, melt-spun Fe-Ga alloy ribbons

Ribbons of Fe100−xGax (x = 15, 17.5, 19.5 and 22.5) were prepared by rapid solidification from the melt. Fe Mössbauer spectroscopy and high resolution neutron diffraction have revealed that Fe100xGax alloys with x = 15 and 17.5 have the disordered bcc (A2) structure even after annealing, but the alloy with x = 19.5 developed the short-range ordered D03 phase when annealed. The x = 22.5 alloys showed mainly D03 phase with a fraction of bcc phase. A fraction of the bcc phase transformed into D03 phase and the long-range ordering of D03 phase was improved after annealing. Fe Mössbauer spectra showed no observable L12 phase in any samples even though less than 1% volume of L12 phases have been found in the annealed samples by neutron diffraction. The additional absorption at hyperfine field of 25 T in x = 22.5 samples was regarded as a result of imperfect D03 structure, rather than a L12 phase.