稀土-铁基磁致伸缩材料具有应变大、能量密度高、换能效率高等优点，是实现电-磁-机械能量转换的理想材料。该类材料中的磁性相（RFe2）具有极强的磁晶各向异性，易磁化方向为<111>，而易生长方向为<100>，因此制备<111>取向的材料是提高磁致伸缩性能的有效途径，同时也是材料制备的难点所在。本课题将强磁场同定向凝固技术相结合，以典型Tb-Fe和Tb-Dy-Fe合金为研究对象，研究初生相（RFe3）和包晶相（RFe2）在强磁场下的取向行为及二者之间的位向关系，建立包晶反应过程中的磁取向理论；考察在强磁场下定向凝固过程中RFe2相的取向行为、材料的组织形貌和性能的演变规律；研究热流方向、磁取向方向和晶体易生长方向对材料组织形貌的影响及其相互关系；在揭示强磁场对材料组织和性能作用机制的基础上，探索利用强磁场制备具有高<111>取向度、磁致伸缩性能显著提高的稀土-铁基材料的方法。

RFe2 (R=rare earth)-based magnetostrictive materials have advantages of large magnetostriction strain, high energy conversion efficiency, and rapid response rate. They can potentially be used as materials of conversion between electromagnetic and mechanical energy. Because the magnetostrictive phase RFe2 in the materials has an easy magnetization axis along its <111> direction, and shows a huge magnetostrictive anisotropy, extensive efforts have been made to achieve sharp and uniform texture along the <111> direction throughout the materials. However, it is difficult to grow RFe2 along the <111> direction, because the RFe2 crystals have a <100> preferred crystallographic direction. Combining high magnetic fields and directional solidification process, aiming on the typical Tb-Fe and Tb-Dy-Fe alloys, the orientation behavior of both RFe3 and RFe2 phase and their relation in high magnetic fields will be studied. The theory of the.magnetic crystal orientation during peritectic reaction process will be proposed. The evolution of the orientation behavior of the RFe2 phase, the microstructure and properties of the materials in high magnetic fields will be studied. The effects of the heat flow direction, magnetic orientation direction, and preferred crystallographic direction on the microstructure and their relation will be investigated. The mechanism of the effects of high magnetic fields on the microstructure and properties of the materials will be studied. A novel method for fabricating the RFe2-based materials with strong <111>-orientation and high magnetostrictive properties will be proposed.