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 1h 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 19.5at.% 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 15at.% Ga ribbon might indicate the existence of some kind of short range ordering. Ribbons developed L12 phase after annealing especially in the Fe 19.5at.% 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 22.5at.% Ga ribbon and the following annealing treatment transformed more A2 phase into D03 phase.