Crystal growth of high magnetostrictive polycrystalline Fe ₈₁Ga ₁₉ alloys

High magnetostrictive Fe ₈₁Ga ₁₉ alloy was prepared by induction heating zone melting method. The microstructure, solute partition behaviour, orientation evolution and magnetostriction are investigated. During the crystal growth process, the initial small grains gradually grow into large columnar crystals, and the solidliquid interface shows slightly concave morphology. The equilibrium solute partition coefficient (k ₀), effective solute partition coefficient (k _e) and solution diffusion coefficient (D) are calculated to be 0.74, 0.76 and 1.04×10 ^-9 m ²/s, respectively. In the steady growth stage, the composition distribution of the FeGa rod is uniform with average level about 18.50 at% Ga, which is close to the nominal composition. The deviation of the 〈001〉 orientation from the axial direction evolves from about 8° to 3° along the growth direction, and the corresponding magnetostriction increases from the initial 180 ppm to the final 305 ppm.