[en] The underlying relation between the magnetostriction (3/2) λ₁₀₀ and Ga concentration for Fe-Ga alloys is an open question. This work presents a systematic structural study of the structure-property dependence of Fe-Ga alloys by transmission electron microscopy and X-ray diffraction. Results show that in the regions where monotonic increases in (3/2) λ₁₀₀ are exhibited, single-phase A2 or D0₃ is found for the slow-cooled alloys. For the alloys in the range 18-21 at.% Ga, quenching extends the single-phase A2 to higher Ga concentrations, thereby continuing to enhance magnetostriction. The sudden decrease in (3/2) λ₁₀₀ near Fe-19 at.% Ga as well as Fe-29 at.% Ga was associated with the formation of phase mixtures. For quenched alloys between 25 and 29 at.% Ga, a phase mixture of (A2 + B2 + D0₃) was found, but the presence of this phase mixture does not seem to have a large effect on magnetostriction