Magnetostriction of the Oriented Crystals in a TbDyFe Alloy

The preferred growth directions of Tb_0.3Dy_0.7Fe_1.95 grown by a super-high temperature gradient zone melting directional solidification technique were examined over a large range of the crystal growth velocity (0.5-30 mm/min). The 110 preferred growth direction was found in most case, and the 112 orientation only existed with a certain solidification condition. The magnetostriction of the110 oriented samples was poor and had no obvious “stress effect”, which exists in 110 perfect crystals according to alculation. The difference of the magnetostriction between the actual and perfect 110 oriented crystal was discussed in detail. The poor magnetostriction of the 110 oriented samples was attributed to the special 109.5°angular with two (111) twin growth mechanism, which resulted in the 114 direction along axis in twins, and only the110 along axis in master.