磁致伸缩合金在航空航天、石油增采和国防建设等领域有重要应用前景。稀土巨磁致伸缩合金性能高（1800ppm），但稀土含量逾60%，成本极高，应用受限。近期报道低成本非稀土FeGa合金性能约300ppm。非稀土（少稀土）磁致伸缩合金高性能化遭遇原理和方法瓶颈。. 我们前期探索发现，在FeGa中添加微量（≤0.2%）强磁晶各向异性稀土元素，并通过快速凝固甩带获得过饱和固溶非平衡组织，性能高达1900ppm，有望成为新型铁基巨磁致伸缩合金。但快速凝固甩带仅获得二维薄带，且择优取向度低。高性能三维晶体制备需同步实现稀土过饱和固溶和沿性能最优方向生长，发展快速定向凝固至关重要。. 本项目重点研究新型铁基巨磁致伸缩合金快速定向凝固方法和晶体定向生长，确定其快速定向凝固行为，阐明亚稳相、择优取向和微结构演变规律及机制，阐明微量4f稀土元素FeGa合金磁致伸缩应变增强作用的物理机制，制备出高性能新型铁基巨磁致伸缩合金晶体，发展快速定向凝固理论与技术。

Magnetostrictive alloys possess important potential applications in aeronautics and astronautics, energy safety and national defense, etc. The rare earth giant magnetostrictive alloys exhibit magnetostriction up to 1800 ppm. But due to the content of rare earth over 60%, the rare earth giant magnetostrictive alloys are too expensive to be used. The recently reported low-cost rare-earth-free FeGa magnetostrictive alloys exhibit the magnetostriction of just 300 ppm. The improvement of the magnetostriction of rare-earth-free (or slight amount of rare earth) magnetostrictive alloys encounters theoretical and technical bottlenecks.. . More recently, we have found that the magnetostriction of FeGa alloys could be improved up to 1900 ppm by the adding slight amount of strong magnetocrystalline anisotropic rare earth elements and by achieving non-equilibrium microstructure with supersaturation of rare earth elements through melt spinning technique. Therefore, the slightly rare earth doped FeGa alloys are expected as advanced iron-based giant magnetostrictive alloys. However, the miecroscopic mechanism of the enhancement of the magnetostriction caused by the slight addition of rare elements keeps unclear. One the orther hand, only two-dimensional ribbons can be produced by the melt spinning technique, with low degree of preferential orientation. In order to obtain three-dimensional crystals of the advanced iron-based giant magnetostrictive alloys, it is required to simultaneously realize the super saturation of rare earth elements and the crystal growth along the direction of the optimal magnetostrictive properties. So, the development of rapid directional solidification (Rapid DS) is of crucial importance.. . This project mainly investigates the rapid directional solidification technique and the control of metastable phase, preferential orientation and microstructure of advanced magnetoelastic materials. The solidification behavior of advanced magnetoelastic materials in the conditions of rapid directional solidification would be revealed. The formation of metastable phase, preferential orientation and the evolution of microstructure, and the corresponding mechanism, would be classified. The microscopic mechanis of the enhancement of the magnetostriction caused by the slight addition of rare elements would be clarified. Then advanced magnetoelastic metallic crystals with large magnetostrain properties would be prepared. Rapid directional solidification technique and theories would be developed.