Research On Texture Control And Magnetstrictive Property In Fe-Ga Alloy Sheet

Magnetostrictive material is a new type of magnetic functional material which is critical.to the national economy and national security.Fe-Ga alloy(Galfenol)is the only one known as magnetostrictive material with excellent magnetostriction coefficient and excellent mechanical properties.Fe-Ga alloy has significant anisotropy,and the magnetostriction coefficient is the largest in<100>direction.Because of the high cost and high eddy current loss of Fe-Ga alloy prepared by single crystal,it is necessary to develop a method of preparing Fe-Ga polycrystal sheet of ?(<100>//RD)with high efficiency and low cost.The rolling method is the most feasible way to obtain Fe-Ga polycrystalline sheet.The key technique for obtaining excellent magnetostrictive Fe-Ga thin strip by rolling is the texture control of secondary recrystallization.The key technique of control secondary recrystallization is to match the microstructure texture and inhibitor harmoniously,but the existing research of Fe-Ga alloy secondary recrystallization control technology inhibited by NbC lacks the research of the regularity of texture evolution and the compatibility of inhibitor,As well as the inhibitor(strength and extinction rate)and Goss({110}<001>)secondary recrystallization are not matching,using the surface segregation to induce and supple the inhibition effect must be heating to 1200?to eliminate residual grain.The technology is complex,when heating to high temperature,the Ga is volatile seriously that is detrimental to the magnetic performance,it is difficult to industrialization.Therefore,It is urgently to develop a more stable and efficient preparation of large magnetostriction coefficient Fe-Ga alloy thin strip with the great Goss secondary recrystallization texture.In this study,Fe-Ga alloy sheet with strong Goss({110}<001>)texture was successfully prepared by conventional hot rolling,cold rolling and annealing process using NbC as intrinsic inhibitor and secondary cold rolling method.And the effect of NbC on the microstructure and texture was studied by X-ray diffraction and backscatter electron diffraction(EBSD).The main findings are as follows:(1)The sub-surface of Fe-Ga-NbC hot-rolled sheet is dominated by {110}<001>Goss texture.The sub-surface after the first cold rolled and the second cold rolled is mainly composed of y-fiber texture(<111>//ND)with strong {111}<112>and ? fiber texture with weak {001}<210>?<010>(<001>//ND),and the sheet is formed into a strong shear zone.The primary recrystallization texture of Fe-Ga-NbC alloy is mainly composed of ?-fiber texture(<001>//RD)with stronger Goss and weaker y-fiber texture(<111>//ND);(2)The secondary recrystallization mechanism of Fe-Ga-NbC alloy accords with HE theory;(3)As the content of NbC increased,primary recrystallization organization become more fine and uniform,the matrix grain and surface grain of high temperature annealing are effectively inhibited so as to realize the perfect secondary recrystallization.By adjusting the content of NbC,this research realize perfect matching of secondary recrystallization and inhibition and eliminate the reliance of the surface energy;(4)With the increase of reduction rate of cold rolling,the orientation degree of secondary recrystallization and magnetostriction coefficient decrease,they can achieve perfect secondary recrystallization,which can provide the theoretical basis for further adjustment of the deformation microstructure;(5)NbC precipitation is controlled by hot rolling,the inhibitor intensity is adjusted,realizing the intensity and the fading rate of inhibitor match with grain boundary diffusion rate of the temperature regions which secondary nucleus selected to initiation and raised.From the perspective of optimization matching of inhibitor and grain boundary,the Fe-Ga alloy thin strip is prepared with perfect Goss texture of secondary recrystallization and the magnetostrictive coefficient reaches 265 ppm;it explores the feasible way to prepare the Fe-Ga alloy thin strip with sharp Goss texture and optimize the secondary recrystallization texture.