Magnetostriction of a (110) oriented Tb_(0.3)Dy_(0.7)Fe_(1.95) polycrystals annealed under a noncoaxial magnetic field

摘要

A (110) oriented Tb_(0.3)Dy_(0.7)Fe_(1.95) alloy rod was annealed at 500 ℃ under a magnetic field of 0.3 T, which was applied 35° away from the rod axis. X-ray diffraction characterization and optical microscopy observation showed that both the crystal orientation and morphologies were retained after magnetic annealing. Magnetic force microscopy images exhibited obvious change of the magnetic domain configurations. The magnetostrictive performance was changed drastically. Saturation axial magnetostriction λ_(‖s) increased from 1023 to 1650 ppm by the ratio of 61.3%, but saturation perpendicular magnetostriction λ_(⊥s) decreased from -802 to -624 ppm. Maximum magnetostrictive strain coefficients d_(33) and d_(31) were found to be enhanced by 29.3% and 32.6%, respectively. In addition, the fields for obtaining both optimum d_(33) and d_(31) decreased, which indicates that better magnetostrictive performance can be achieved at lower external fields after magnetic annealing.