Crystallographic Textures In Rolled And Recrystallized Fe₈₁Ga₁₉ Sheet

Fe-Ga alloy has attracted much attention as a promising magnetostrictive material for actuators and sensors in terms of combining large saturation magnetostriction, low saturation magnetic field, weak temperature dependence as well as high mechanical strength and good ductility. Fe-Ga alloy exhibits a significant magnetostrictive anisotropy with the largest magnetostriction coefficient close to400ppm along<100> direction and only about40ppm along<111> direction. Current preparation methods such as single crystal growth and directional solidification are inefficient, and further sheet cutting is necessary to decrease eddy current loss. Rolling is more efficient for sheet forming, and it is, therefore, desirable to produce η(<100>//RD)textured Fe-Ga polycrystalline sheets by rolling procedure to optimize the magnetostrictive performance.In this study, Fe81Ga19alloy sheet of good texture feature was prepared through conventional rolling procedure which combined hot rolling, normalizing, cold rolling and annealing. Based on solving the cold formability, the research was focused on the two aspects. The effect of initial grain sizes and cold rolling reductions on primary recrystallization textures and the effect of initial grain sizes and heating rates on second recrystallization textures were studied. This paper establishes an important foundation for the development of high grade Fe-Ga alloy sheet.Primary recrystallization texture consists mainly of Goss ({110}<001>) and γ fiber changed from cold rolling texture dominated by γ fiber (<111>//ND) and weak a fiber (<110>//RD). Initial grain sizes after normalizing has a great influence on primary recrystallization microstructure and texture. The analysis of recrystallization texture shows that grain sizes after normalizing of78μm and cold rolling reductions of70%is favor of obtaining more Goss.In order to get strong and single Goss texture through second recrystallization annealing, we make a study that grain size after normalizing(78μm and158μm) and heating rate(25℃/h,50℃/h,100℃/h and200℃/h) have a big effect on second recrystallization microstructure and texture. The result of this research indicates that grain size after normalizing of78μm and heating rate of25℃/h is a prospective route to get best texture. On the other hand, saturated magnetostrictive of specimens by this route can reach154ppm.Thus, the present results provide a prospective route to efficiently optimize the recrystallization and second texture of Fe-Ga alloy through reasonable rolling process flow and the annealing process.