Magnetic Domain and Magnetic Properties of Tb–Dy–Fe Alloys Directionally Solidified and Heat Treated in High Magnetic Fields

(Tb _0.27 Dy _0.73 ) _1.04 Fe _1.95 alloys directionally solidified in a 4 T high magnetic field were heat treated in various high magnetic fields. Changes in magnetic domain structure, magnetostriction, and magnetization of the alloys were investigated. The alloys treated at 12 T showed the highest magnetostriction, followed in descending order by the alloys treated at 0, 6, 3, and 9 T. The alloys treated at 12 T showed the highest light and dark contrast in the domain image, followed in descending order by the alloys solidified at 6, 0, 3, and 9 T. The change in magnetostriction can be mainly attributed to the alteration of the light and dark contrast in the domain image induced by the high magnetic fields. It can be proved that the high magnetic field can be effectively applied to the directionally solidification and heat treatment processes of Tb-Dy-Fe alloys to improve their magnetostrictive performance.