Neutron diffraction studies of magnetostrictive Fe–Ga alloy ribbons

Melt-spun Fe–Ga ribbons were prepared and some ribbons were annealed at 1000 °C for 1 h then
slowly cooled to room temperature. X-ray diffraction patterns revealed no evidence of texture and
only bcc phase in the as-quenched ribbons. However, high-resolution neutron diffraction patterns
gave more information on the structure of these ribbons. Only diffractions from the disordered bcc
A2 phase were found in as-quenched ribbons with 15, 17.5, and 19.5 at. % Ga content, without any
trace of satellite peaks or splitting peaks from the proposed Ga–Ga pairing superlattice structure.
The broadening of the base of the �110� peaks for all samples except the as-quenched 15 at. % Ga
ribbon might indicate the existence of some kind of short range ordering. Ribbons developed L12
phase after annealing especially in the Fe 19.5 at. % Ga ribbon where the formation of L12 phase
reduced the Ga content in the remaining A2 phase and decreased its lattice parameter dramatically.
D03 phase formed in the as-quenched 22.5 at. % Ga ribbon and the following annealing treatment
transformed more A2 phase into D03 phase.