Tailoring nano-heterogeneity to enhance magnetostriction in Goss grain-oriented Fe81Ga19 alloy thin sheets by aging treatment

The magnetostriction of Fe–Ga thin sheets can be significantly improved by secondary recrystallization, but the effect of the nano-heterogeneity on the magnetostriction of Fe–Ga thin sheets with preferred texture is still an open question. This paper studies the feasibility of tailoring nano-heterogeneity to enhance the magnetostriction of <001>-oriented Fe–Ga thin sheets by aging treatment. The secondary recrystallization of Goss ({110}<001>) texture with magnetostriction of 220 ± 12 ppm is achieved in Fe81Ga19 thin sheets after annealing at 950 °C. The magnetostriction and magnetic properties exhibit nonlinear changes with the increase of aging temperature. A peak magnetostriction of 244 ± 5 ppm is obtained in Fe81Ga19 thin sheets after aging at 450 °C, about 11% more than that of Fe–Ga thin sheets after secondary recrystallization. The effect of aging treatment on the magnetostriction of Fe–Ga thin sheets depends on the characteristics of the nano-scale L60 phase and causes lattice distortion. The increase of the volume fraction of the nano-scale L60 phase at the aging temperature of 450 °C leads to a much larger distortion and enhancement of the magnetostriction. As the aging temperature is lower than 400 °C or higher than 550 °C, the decrease of volume fraction or the coarsening of L60 phases, respectively, results in the decrease in the distortion of the A2 matrix.