Investigation on the orientation transition of oriented magnetostrictive TbDyFe crystals

〈110〉 and 〈112〉 TbDyFe magnetostrictive oriented crystals were prepared by the zone-melting unidirectional solidification method at 240 mm/h and 720 mm/h respectively. 〈112〉 oriented crystals were also obtained with 〈110〉 oriented seeds with the same technique as for growing the 〈112〉 oriented crystals. It is confirmed that this technique is stable for growing the oriented crystals in the TbDyFe alloys. Meanwhile, the variation of orientation, the solidification morphology and the magnetostriction were studied during the transition from 〈110〉 oriented seeds to the 〈112〉 oriented crystal growth. As the growth speeds up, the preferred orientation changed from 〈110〉 to 〈112〉and its morphology develops from of initial cellular to dendritic gradually. When an axial compressive pre-stress of 10 MPa is applied, the magnetostriction at the bottom, the middle and the top are 972×10 ^-6, 918×10^-6 and 900×10^-6 at 100 mT respectively. The middle sections with mixed orientations have the same high magnetostriction performance as those with a single preferred orientation, which may be due to its celluar-dendritic morphology.