Effect of oxygen impurity on magnetostriction of directionally solidified Tb0.3Dy0.7Fe1.8

A giant magnetostrictive alloy, Terfenol-D, is known to have high magnetostriction and low anisotropy energy. However, oxygen contamination deteriorates the magnetic and magnetoelastic properties of giant magnetostrictive material. Oxygen impurity can originate from the raw materials and from the environment during the manufacturing process. Therefore the effect of oxygen on the magnetostrictive properties and the microstructure of the Tb_0.3Dy_0.7Fe_1.8 alloy were quantitatively investigated. The results demonstrated that as oxygen content increased, magnetostrictive strain and magnetostrictive coefficient decreased. These effects were discussed from the standpoint of microstructure.