Crystalline Fe 25Zn 75 powder alloys ( Γ 1 phase) have been prepared by mechanical alloying of pure elemental powders. A crystalline Fe 27.9Zn 72.1 alloy (Γ phase) was obtained after adequate annealing. The Mössbauer spectra at room temperature displayed three doublets before annealing, corresponding to iron atoms located at the outer tetrahedral, inner tetrahedral and octahedral sites in the unit cell of Fe 25Zn 75. For the annealed sample, two doublets associated with iron atoms located at two tetrahedral inequivalent sites in the unit cell of Fe 27.9Zn 72.1 were observed. This Γ 1-to-Γ-phase transition was confirmed by X-ray diffraction and Mössbauer spectroscopy measurements.