Magnetic anisotropy and magnetostriction in nanocrystalline Fe–Al alloys obtained by melt spinning technique

A study about the magnetic anisotropy and magnetostriction in ribbons of composition Fe₈₁Al₁₉ and Fe₇₀Al₃₀ obtained by the melt spinning technique is presented. The hysteresis loops indicate that the easy magnetization direction lies in both cases on the plane of the ribbon. Torque magnetometry measurements show that the in-plane magnetic anisotropy constant results 10100 J m⁻³ and 490 J m⁻³ for the Fe₈₁Al₁₉ and Fe₇₀Al₃₀ respectively. After a thermal treatment of 2 h at 473 K to remove the residual stresses, the in-plane magnetic anisotropy constants falls down to 2500 J m⁻³ in the first composition and remains the same in the second one, while the easy direction remains the same. Measurements of the magnetostriction and the residual stresses of both ribbons allow us to explain the above mentioned results about the magnetic anisotropy and to conclude that the residual stresses via magnetostriction are the main source of magnetic anisotropy in the case of Fe₈₁Al₁₉ ribbon but they do not influence this property in the ribbon of composition Fe₇₀Al₃₀. - Highlights: • The origin of magnetic anisotropy of Fe₈₁Al₁₉ and Fe₇₀Al₃₀ ribbons has been studied. • The magnetic anisotropy lies in the plane of the ribbons. • A huge difference in magnetic anisotropy between two ribbons has been observed. • Magnetostriction and residual stresses explain the magnetic anisotropy in Fe₈₁Al₁₉ ribbon