Magnetostrictive properties of body-centered cubic Fe-Ga and Fe-Ga-Al alloys

The magnetic and magnetostrictive properties of Fe_1-xGa _x and Fe_1-x-yGa_xAl_y (a+y<0.3) single crystals were measured under compressive stresses up to 120 MPa and in magnetic fields up to 1 kOe. Values of λ₁₀₀ exceeding 200 ppm were observed in samples of Fe ₈₃Ga₁₇ from 180 K to room temperature. Only a small monotonic decrease in magnetostriction with temperature was found. On the other hand, λ₁₁₁ maintained small negative values close to those of b.c.c. Fe. In all cases, no higher order magnetostrictive terms were detectable. With 15 to 20 atomic percent replacement of Fe by Ga, the magnetizations remain high (M, ≅1.8 T) and the magnetic anisotropies reduced (K₁≅10⁴ J/m³). Values of the `stiff´ (high magnetic field) Young´s modulus, Bulk modulus, Poison´s ratio, and elastic constant C₁₁ -C₁₂ for Fe₈₅Ga₁₅ at room temperature are, respectively, 77 GPa, 111 GPa, 0.38, and 56 GPa