Recrystallization, texture evolution, and magnetostriction behavior of rolled (Fe₈₁Ga₁₉)₉₈B₂ sheets during low-to-high temperature heat treatments

In order to study the texture evolution and magnetostriction behavior in the rolled Fe–Ga–B sheets during the heat treatments from low to high temperatures, (Fe₈₁Ga₁₉)₉₈B₂ sheets were prepared and investigated. The phase structure, recrystallization, grain size, texture evolution, and magnetostriction behavior during the annealing from 525 to 1200 °C for 1–5 h were investigated using X-ray diffraction, electron backscattering diffraction, and standard strain-gauge measurements. Results indicated that the primary recrystallization temperature for 1-h annealing was found as 525–575 °C in (Fe₈₁Ga₁₉)₉₈B₂ sheets. Annealing the sample below 575 °C for 1 h, the release of rolling stress and increase of 〈100〉 η-fiber texture during the primary recrystallization jointly resulted in a rapid improvement in magnetostriction. After annealed between 575 and 1100 °C for 1 h, the grains of the sheets underwent a normal growth, and the three (α-, γ- and η-fiber) types of textures kept an approximate balance, leading to a plateau of magnetostriction around 75 ppm. When the abnormal grain growth proceeded above 1100 °C for 1 h, the proportion of η-fiber texture markedly increased, and the magnetostriction was subsequently increased to 97 ppm. For longer annealing durations, the strong ideal cube texture (η-fiber) was firstly formed and then changed to undesired texture (γ-fiber), producing a corresponding magnetostriction peak of 136 ppm at 2 h for the annealing at 1200 °C. The clear correlation among heat treatments, recrystallization, texture, and magnetostriction provides an essential understanding for Fe–Ga–B alloy sheets.