Magnetostriction and Hysteresis of (Tb,Dy,Ho)Fe 2 Alloys

The Tb/Dy ratio of Tb0.30Dy0.70Fe1.95 giant magnetostrictive alloy was shifted away from 0.30/0.70 to 0.36/0.64 to enlarge the operating temperature range. However, the magnetostriction was reduced under low magnetic field and its hysteresis was enlarged with the shift of Tb/Dy ratio. Ho addition improves the magnetostriction under low magnetic field and reduces the hysteresis of TbxDyyHozFe1.95 (x+y+z=1). The crystal structure, lattice constant, Curie temperature, spin reorientation temperature, magnetization, magnetic anisotropy and magnetostriction of TbxDyyHozFe1.95 alloys were investigated. X-ray diffraction patterns demonstrate that all the samples possess MgCu2-type cubic Laves structure. The lattice parameter, Curie temperature and magnetic anisotropy constant K1 decreased with increasing Ho concentration. The hysteresis represented by the width of magnetostriction versus the applied field was reduced due to the addition of Ho. At a compressive stress of 10 MPa and a magnetic field of 1000Oe, the addition of Ho to the ternary TbxDyyFe1.95 compound reduced the width of magnetostriction by 25% for Tb0.296Dy0.472Ho0.232Fe1.95 and by 27% for Tb0.296Dy0.472Ho0.232Fe1.95 compared to the Tb0.36Dy0.64Fe1.95 alloy, while the strains were reduced by only 3% and 9%.