NiMnGa铁磁形状记忆合金因具有大磁致应变等特殊功能特性，在航空航天、国防工业、机械电子等领域具有重要应用前景。已有研究表明，该磁致应变值强烈依赖于合金的凝固择优取向和马氏体变体形态；马氏体相变温度的一致性则由凝固宏观成分偏析所决定。然而，凝固择优取向规律与机制，成分偏析控制，以及马氏体变体调控等尚不明确。该项目以具有超大磁致应变（20%以上）潜力的T型马氏体结构的NiMnGa合金为研究对象，深入研究NiMnGa合金的凝固择优取向和成分偏析控制以及马氏体变体调控等关键科学问题，揭示影响超大磁致应变的关键控制因素，制备出<001>取向、无宏观偏析、单变体的NiMnGa合金单晶，并实现20%以上的大磁致应变，为其在航空航天等领域应用奠定重要基础。

NiMnGa ferromagnetic shape memory alloys have important application prospect in the field of space industry, defense industry, mechanical and electrical industry due to large magnetostrain and other novel physical functionalities. Studies have shown that the magnetostrain is dependent on solidification preferred orientation and martensitic variants. Moreover the inevitable composition segregation caused by solidification affects the martensitic transformation temperature. However all the mechanism of solidification preferred orientation, the control of composition segregation and the regulation of martensitic variants are unclear. In this project, based on NiMnGa alloys with potential large magnetostrain (more than 20%) in tetragonal martensite, it is aimed to study solidification preferred orientation control, composition segregation control and martensitic variants regulation in order to reveal the intrinsic key factors of large magnetostrain, then obtain NiMnGa single crystal along <001> with single variant and non-macrosegregation which achieves more than 20% magnetostrain. That will lay an important foundation of the application in many fields.