Disorder trapping in gas quenched magnetostrictive Fe–Ga alloys

The structural and magnetic properties of Fe100−xGax (x = 17, 20, 23, 25, 27 and 30) in heat treated (950 °C/10 h) and quenched condition were studied. While the X-ray diffraction patterns and the microstructures indicate that all the alloys contain only the disordered α-Fe (A2 phase), whereas, the Mössbauer spectra reveal that the alloys with x ≥ 25 contain minor fractions of ordered L12 and DO3 phases. The room temperature saturation magnetostriction increases for the initial concentrations of Ga (x = 17–23) and then decreases for higher concentrations. The effect of quenching in suppressing the formation of ordered phases (L12 and DO3) and in retaining the high temperature disordered (A2) phase is attributed to be the main reason for the increase in the magnetostriction due to Ga addition.