微量稀土元素掺杂引起Fe-Ga合金大磁致伸缩性能的研究进展

Research Progress on the Enhanced Magnetostrictive Properties of Fe-Ga Alloys Induced by Trace Rare Earth Doping

磁致伸缩材料是一类新型智能材料,在机器人、传感器和位移控制器等领域有重要的应用价值。与传统磁致伸缩材料和已商业化巨磁致伸缩材料相比,新型Fe-Ga磁致伸缩材料具有更易实用化的优良特性和应用前景,例如低磁场下应变高、力学性能好、对温度的依赖性低、价格低廉等,因而Fe-Ga合金成为凝聚态物理和材料科学领域的研究热点。早期关于Fe-Ga合金的研究主要集中在单晶Fe-Ga合金,但其制备工艺复杂、成本高,难以广泛应用。为拓宽Fe-Ga合金的应用范围,人们开始关注多晶Fe-Ga合金。然而,采用常规熔炼法制备的多晶Fe-Ga合金磁致伸缩系数很低,限制了其实际应用。因此,提高多晶Fe-Ga合金的磁致伸缩性能成为该类合金能广泛应用的关键。合金结构决定合金性能,合金结构又与合金成分和制备工艺密切相关。为提高多晶Fe-Ga合金磁致伸缩系数,研究者做了大量工作。近年来,具有特殊4f电子层结构的稀土元素因具有优异的磁学性质而引起人们的广泛关注。人们将微量稀土元素Tb、Dy、Ce、Y、Sm、Pr等掺杂到Fe-Ga合金中,发现Fe-Ga合金的磁致伸缩性能得到明显的改善。然而到目前为止,有关稀土掺杂Fe-Ga合金的磁致伸缩机制仍不一致。一些研究者认为磁致伸缩性能的改善是由于稀土掺杂导致Fe-Ga合金形成富稀土相,也有研究者认为主要是由于稀土掺杂使合金沿〈100〉择优取向。近年来一些研究者认为,大磁致伸缩主要源于稀土原子进入Fe-Ga合金的A2基体中引起的大四方畸变。但是稀土掺杂如何使Fe-Ga合金中A2基体产生大四方畸变以及掺杂稀土与A2基体中四方纳米异质结构modified DO3相是如何作用的,这些问题仍不清楚。本文首先分析了人们选择稀土元素掺杂Fe-Ga合金的原因;然后分析了稀土元素掺杂对Fe-Ga合金性能的影响;最后详细综述了稀土元素掺杂引起Fe-Ga合金大磁致伸缩性能的理论机制,同时展望了该类合金未来的发展方向。

Magnetostrictive material is a new kind of smart material,which has important application value in robot,sensor and displacement controller.Compared with traditional magnetostrictive material and commercialized giant magnetostrictive materials,the new Fe-Ga magnetostrictive material has excellent characteristics of more practical and application prospect,such as high strain at low magnetic field,good mechanical pro-perty,low temperature dependence,low cost,and so on.So Fe-Ga alloy become a hot research topic in the field of condensed matter physics and materials science.The early researches related to Fe-Ga alloy mainly focused on the single-crystal Fe-Ga alloy.But It’s preparation process is difficult and the cost is high,so it is difficult to be widely used.In order to broaden the application range of Fe-Ga alloy,people begin to pay attention to polycrystalline Fe-Ga alloy.However,the low magnetostrictive coefficient of polycrystalline Fe-Ga alloy prepared by conventional mel-ting method limits its practical application.Therefore,improving the magnetostrictive property of polycrystalline Fe-Ga alloy is the key to its wide application.The structure of the alloy determines its properties,and the structure of the alloy is closely related to the composition and preparation process of the alloy.In order to improve the magnetostrictive coefficient of polycrystalline Fe-Ga alloy,researchers have done a lot of research work.In recent years,rare earth elements with special 4f electron structure have attracted more and more attention in the field of magnetostriction due to their excellent magnetic properties.Light trace rare earth element Tb,Dy,Ce,Y,Sm and Pr were doped into Fe-Ga alloy,and it was found that the magnetostrictive property of Fe-Ga alloy was significantly improved.However,the conclusion about the magnetostriction mechanism of rare earth doped Fe-Ga alloy is still inconsistent.Some researchers believe that the improvement of magnetostrictive properties is due to the formation of rare earth rich phase in Fe-Ga alloy due to the doping of rare earth,while others believe that the main reason is that the alloy has a preferential orientation along〈100〉due to the doping of rare earth.In recent years,some researchers believe that the large magnetostriction is mainly due to the large tetragonal distortion caused by the rare earth atoms entering the A2 matrix of Fe-Ga alloy.However,it is still not clear how rare earth doping cause large tetragonal distortion of A2 matrix in Fe-Ga alloy and what interaction of rare earth dopants with tetragonal nano-heterogeneities modified DO3 phase in A2 matrix.In this paper,we first analyzed the reason of selection of rare earth elements doped Fe-Ga alloy.Then,the influence of rare earth element doping on Fe-Ga alloy property was analyzed.Finally,the theoretical mechanism of large magnetostrictive property of Fe-Ga alloy caused by rare earth element doping was summarized in detail,and the future development direction of this kind of alloy was prospected.