Effect of thermal history and gallium content on magneto-mechanical properties of iron gallium alloys

Thermo-mechanical and magneto-mechanical properties were studied for iron substituted with 17.5, 19.1 and 20.5 at.% gallium quenched from 1000 °C and subsequently heated to 400 °C and slow-cooled. A phase change was observed in the 19.1 and 20.5 at.% Ga quenched samples upon heating. X-ray diffraction studies on the single crystal samples showed that the phase change observed was due to the precipitation of D03 upon heating from the quenched state. Magneto-mechanical characterization showed that the presence of ordered D03 phase in the slow-cooled 19.1 at.% Ga sample reduced the saturation magnetostriction in comparison to the quenched sample of same composition. The magneto-mechanical properties of both the quenched and slow-cooled 17.5 at.% Ga samples were similar owing to the presence of only the disordered A2 phase in both these samples.