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 the [110] oriented samples was poor and had no obvious "stress effect", which exists in [110] perfect crystals according to calculation. 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 the [110] along axis in master.