Study Of Magnetostrictive Material Fe-Ga Alloys

In this paper,the phase structure and magnetostriction of Fe-Ga alloys have been researched by different ingredients and preparation processes,in order to find out the relationship between microstructure,process methods and properties.The precursor ingots with composition of Fe_100-xGa_x(x=16,17,18,19,20) was prepared by are melting under inert atmosphere.Fe_100-xGa_x(x=16,17,18,19,20) alloys were prepared by blow-casting method.Another Fe_100-xGa_x(x=17,18,20) alloys were fabricated using the technique of directional solidification.1.The magnetostriction property is significantly affected by the content of Ga in alloys.The maximum magnetostriction of 62×10^-6 was obtained in Fe₈₂Ga₁₈ alloys. The content of Ga at 16%has minimum magnetostriction of 39×10^-6.2.The Fe₈₂Ga₁₈ alloys prepared by blow-casting method while applied magnetic field perpendicular to the grain orientation have strong magnetostriction property.The saturation magnetostriction reached 92×10^-6 at 35KA/m.The magnetostriction of specimens after heat treatment has a significantly drop,especially the specimen after annealing treatment.The drop is attributed to the unsymmetrical DO₃ phase transformed from A2 phase,which restrict the magnetostriction of alloys.Therefore the alloys prepared by blow-casting methos can restrict the formation of DO₃ phase, retain relatively high magnetostriction.3.The magnetostriction of Fe-Ga alloy is not only determined by phase structure, but also has strong irrelevant with the orientation of grains.The Fe-Ga alloys prepared by directional solidification are constituted by columnar crystal,which orientation along the temperature gradient.The size of columnar crystal reach the range of 140～400.The phase structure is analysed by transmission electron microscopy.There are mainly A2 phase and additional B2 super lattice.It also found that the strain of alloys,which along the axis parallel to the temperature gradient are three times larger than those along the axis perpendicularly to the TG.It concluded that the magnetostriction has strongly affected by the orientation of grain and applied magnetic field.It can be expected that the alloys prepared by blow-casting,which grain orientation is parallel to the applied magnetic field,the saturation magnetostriction can reach 270ppm.