The Study Of Microscopic Structure And Magnetostriction Of Deep Supercooled Fe-Ga Alloys Solidificated In Magnetic Field

The under-cooling Fe₈₁Ga₁₉alloys were prepared by glass fluxing combined withsuperheating cycling method, of which the degree of super-cooling is198K,270Kand300K respectively. Directional stimulate the under-cooled alloy ingot into a rodin homemade directional solidification device and study the microstructure andmagnetostriction. Introducing magnetic field on the basis of the existing device inorder to obtain the Fe₈₁Ga₁₉rod solidificated in magnetic field. Study the effect ofmagnetic field on the microscopic structure and magnetostrictive of Fe-Ga alloy rod.The method was applied to the third element B added Fe-Ga alloy, and study themicrostructure and magnetostriction. Study found that:For under-cooling Fe₈₁Ga₁₉alloy ingot, the grain size increase with the increaseof degree of under-cooling. The grains arranged along the certainly direction, showsobviously [110] preferred orientation.After directional stimulate, there have no highly developed columnar crystal inthe microstructure of supercooling Fe-Ga alloy, but the bottom fine-grain layer,columnar crystal and the equiaxial crystal instead. The alloy with undercooling of198K have [100] direction as its axial preferred orientation, with DO₃and A₂phasein crystal.the alloy with undercooling of270K has preferred orientation of [110]orientation, crystal composed mainly by the A₂and modified-DO₃phase.Undercooling increased to300K, alloy is mainly composed of A₂phase, but withinthe matrix there are a number of dislocation nets. With the increasing of aundercooling, the saturation magnetization of strength, saturation magnetization fieldand coercive force of radial direction were decreased. the magnetostrictive ofundercooling Fe-Ga alloy improved obviously after directional stimulated, the alloywith undercooling of270K have the highest magnetostrictive value by150ppm.Based on the results of the above, imposes a magnetic field perpendicular to theaxia among the process of directional stimulated for the alloy with undercooling of270K. found that the existence of the magnetic field affect the grain size and axialorientation of alloy slightly. MFM research shows that magnetic field make themagnetic domain of alloy arranged along the radial direction, its shapes shift frommaze to strip with the width increased. The existence of the magnetic field makes themagnetostrictive of alloy increased greatly, and with the increase of the magneticfield strength, magnetostrictive value increases, up to210ppm. The study of directional stimulate and solidificated in magnetic field forunder-cooling (Fe₈₁Ga₁₉)90B10alloy found that: the microstructure composed mainlyby A₂phase, modified-DO₃phase and Fe₂B phase, axial preferred orientation is [110]orientation. Compared to B added before, the lattice constant of alloy increased, andincreasing with the increasing of undercooling. The alloy which has uncooling of270K has the highest magnetostrictive value is of80ppm. The existence of the magneticfield promote the separation of B-rich and Ga-rich phase in solidificationorganization, compared to magnetic field added before, magnetostrictive risesomewhat, but little.