Magnetostriction of ⟨110⟩ oriented crystals in the TbDyFe alloy

<110> oriented crystals of a TbDyFe magnetostrictive alloy have been successfully prepared by zone melting unidirectional solidification with a large velocity range from 30 to 720 mm/h. The solidified morphologies and the magnetostriction have been investigated. It was found that <110> preferred orientation can form in the TbDyFe alloy with planar, cellular and dendritic solidified morphologies. The satisfactory magnetostrictive property of 1965X10(-6) was obtained under 15 MPa pre-stress in the <110> oriented sample with a velocity of 240 mm/h. An obvious magnetostriction jump effect was observed in the <110> oriented crystals with high velocity (nugreater than or equal to120 mm/h). Conversely, no magnetostriction jump effect appeared in the low velocity grown samples (nu=30 mm/h) also with an excellent <110> orientation. Two kinds of twin growth mechanism are proposed. The single-{111}-twin system growth leads to the magnetostriction jump effect, and the two-{111}-twin system growth results in a lack of the magnetostriction jump effect. The experimental data are basically consistent with the theoretical magnetostriction values, roughly calculated by the two kinds of the twin growth mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.