The preferred orientation, microstructure and magnetostriction in directionally solidified TbDyFe alloys

The device of zone melting directional solidification has been used to investigate the preferred orientation, microstructure and magnetostriction of Tb_0.3Dy_0.7(Fe, M)1.95 (M=Al, Mn, B) metallic compound. When the temperature gradient G_L≈700 K/cm, the growth velocity V ≤1 mm/min, the crystal grows in plannar interface, 1< V ≤6 mm/min, in cellular morphology; v=8 - 12 mm/min, in primary dendrite; V > 15 mm/min, in developed dendrite. As V=12 mm/min G_L≈1000 and 400 K/cm, the crystal grows in cellular morphology developed dendrite, respectively. Crystals in cellular morphology are 〈110〉 preferred orientation and poor magnetostrictive property. Crystals in primary dendrite with 〈112〉 preferred orientation, have a good performance, the maximum value of magnetostriction (λ) is 0.00175. Crystals in developed dendrite with part 〈112〉 orientation have an inferior property than the former.