Abstract:Rapidly solidified Fe_100-xGa_x (x=16-20) alloy rods were prepared by induction melting and copper mold casting under the protection of inert gases. The optical microscopy observation shows that the large and elongated columnar grains grow along the radial direction, which is parallel to the temperature gradient direction. The <110> preferred orientation texture along the axial direction of the rod was detected by XRD. With the increase of Ga content, the saturation magnetization (M_s) of the alloys decreases distinctly and the dynamic response in low magnetic field increases drastically, the maximum longitudinal saturation magnetostriction for as-cast Fe₈₂Ga₁₈ alloy rods is 92×10^-6 under an applied magnetic field strength of 30 kA/m. The large magnetostriction of Fe_100-xGa_x alloys is attributed to the rapidly solidified disordered A2 phase and the high concentration of short range order of Ga atom clusters, which are arranged in the <100> direction and finally trigger the formation of modified-DO₃ structure, just as shown by the split of the (200) diffraction peak. Ordered DO₃ phase is not conducive to the magnetostriction.

Key words: magnetostriction; rapid solidification; Fe-Ga alloy; oriented polycrystalline; microstructure