Hysteresis and magnetostriction of TbxDyyHo1-x-yFe1.95 [112] dendritic rods

The magnetization and magnetostriction of a variety of 3/16-in.-diam Laves phase rods of Tb(x)Dy(y)Ho(1-x)2(y)Fe(1.95) grown in the form of [112] orie nted dendritic compounds were measured as a function of applied magnetic fi eld -3000<H<3000 Oe and compressive stresses of 22 and 47 MPa at room tempe rature. Compared to Terfenol-D (Tb0.3Dy0.7Fe1.95), the widely used room tem perature magnetostrictive material, Ho containing alloys can have substanti ally lower hysteresis with only slightly lower magnetostriction. The Ho con centration was kept relatively small (less than or equal to 0.3) to avoid a substantial decrease in the magnetostriction, while the ratio of x and y w as chosen to examine alloys spanning the line of minimum magnetic anisotrop y. Most of the compositions have twice the Ho content of the previous study . As expected, alloys with higher Ho concentrations showed narrower hystere sis curves. The data shows that at 22 MPa, the Tb0.28Dy0.57Ho0.15Fe1.95 com position has a minimal (3%) loss of magnetostriction, while the hysteresis width decreased by 15%. Between 15% and 20% Ho content, the magnetostrictio n drops abruptly. For alloys with a fixed Ho concentration, the strain show ed a peak near the expected anisotropy minimum, but the hysteresis width al ways increased with increasing Tb content. (C) 1999 American Institute of P hysics. [S0021-8979(99)23408-1].