Influence of rare earth element terbium doping on microstructure and magnetostrictive properties of Fe81Al19 alloy

Abstract Fe81Al19Tbx (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4) alloys were prepared by anon-consumable vacuum arc melting technique under an inert argon gas atmosphere. The microstructures of the alloys were studied by X-ray diffraction (XRD) and scanning electron microscopy with an energy dispersive spectroscopy (SEM/EDS). The magnetic properties and magnetostriction coefficients of the alloys were measured by vibrating sample magnetometer (VSM) and differential resistive strain sensor, respectively. The results show that the Fe81Al19 alloy consists of a single A2 phase with bcc structure, whereas the Tb doped Fe81Al19 alloys are composed of the A2 phase and a small amount of rare earth-rich phase. The doping of the rare earth element Tb makes the Fe81Al19 alloy preferentially oriented along with the crystal direction. With the increase of Tb content, the magnetostriction coefficient of the alloy first increases and then decreases. When x0.1, the magnetostriction coefficient reaches the maximum, which is 146 × 10–6. Compared with the as-cast Fe81Al19 alloy (27 × 10–6), it has increased by 441%. The increased magnetostrictive properties is mainly attributed to the preferred orientation along of A2 phase of the Tb doped Fe81Al19alloysand lattice distortion caused by the small amount of rare earth atoms entering the Fe-Al alloy lattice.