MAGNETOSTRICTION OF THE ORIENTED CRYSTALS IN A TBDYFE ALLOY

The preferred growth directions of Tb0.3Dy0.7Fe1.95 grown by a super-h igh temperature gradient zone melting directional solidification techn ique 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 solidific ation condition. The magnetostriction of the [110] oriented samples wa s poor and had no obvious ''stress effect'', which exists in [110] per fect crystals according to calculation. The difference of the magnetos triction between the actual and perfect [110] oriented crystal was dis cussed in detail. The poor magnetostriction of the [110] oriented samp les was attributed to the special 109.5 degrees angular with two (111) twin growth mechanism, which resulted in the [114] direction along ax is in twins, and only the [110] along axis in master.