Magnetostriction and structural characterization of Fe-Ga bulk alloy prepared by copper mold casting
(1. State Key Laboratory of Gansu Advanced Nonferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Wenzhou Pump & valve Engineering Research Institute of Lanzhou University of Technology,
Wenzhou 325105, China)
Lanzhou University of Technology, Lanzhou 730050, China;
2. Wenzhou Pump & valve Engineering Research Institute of Lanzhou University of Technology,
Wenzhou 325105, China)
Abstract: Rapidly solidified Fe100-xGax (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 (Ms) 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 Fe100-xGax 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