TiNi记忆合金表面NiFe纳米薄膜的大弹性应变及磁学性能调控研究

Adjusting physical and chemical properties of the material via elastic strain has attracted great attention. The elastic strain was often generated by doping or lattice mismatch with the film and the substrate. The elastic strain of NiFe nano-film was adjusted by shape memory effect of SMAs in this project. The tensile elastic strain of NiFe nano-film on TiNi is about 3.5%, and the compressive elastic strain is about 1.5%. The effect of elastic strain on magnetic properties of NiFe film was researched. In this project, we will research the process on adjusting the elastic strain of NiFe films by shape memory effect of TiNi SMAs. The in situ deformation behaviors of the NiFe films will be observed. The mechanism of large elastic strain of NiFe film will be clarified. The magnetic properties of NiFe film will be adjusted by shape memory effect of SMAs. The mechanism of magnetic properties adjusted by elastic strain will be clarified.

利用弹性应变调控材料的物理化学性能受到广泛关注，以往人们通过元素掺杂或膜与基体的晶格错配产生弹性应变，其产生的弹性应变较小且很难连续调控。本课题巧妙的利用马氏体态TiNi记忆合金作为基板，获得了保留大弹性应变的NiFe纳米薄膜。TiNi记忆合金表面NiFe纳米薄膜可保留3.5%的拉伸弹性应变，1.5%的压缩弹性应变，且可连续调控，通过弹性应变成功调控NiFe纳米薄膜的饱和磁化强度。本项目拟研究TiNi记忆合金表面多晶NiFe纳米薄膜呈现大弹性应变及塑性变形的特征和机制、NiFe纳米薄膜与TiNi记忆合金协同变形的特征和机制、弹性应变对多晶纳米薄膜磁学性能影响的特征和规律，揭示TiNi记忆合金表面NiFe薄膜大弹性应变的本质特征，阐明弹性应变调控磁学性能的物理机制，可望获得高质量原创学术成果。

利用弹性应变调控材料的物理化学性能受到广泛关注，以往人们通过元素掺杂或膜与基体的晶格错配产生弹性应变，其产生的弹性应变较小且很难连续调控。本课题巧妙的利用马氏体态TiNi记忆合金作为基板，获得了保留大弹性应变的NiFe纳米薄膜。本项目主要研究TiNi记忆合金表面NiFe薄膜的大弹性应变、塑性变形特征与机制，NiFe薄膜与TiNi基底协同变形行为及弹性应变调控NiFe纳米薄膜磁学性能及其机制。NiFe薄膜的大弹性应变与TiNi基底的马氏体再取向变形机制密切相关，其有效抑制薄膜早期塑性变形，使其展现3.9%的拉伸弹性应变，2.1%的压缩弹性应变，其应变连续可调控。TiNi基体由多变体马氏体，变形后，发生再取向，转变为单一取向马氏体，与纳米薄膜协同变形。NiFe纳米磁性薄膜的饱和磁化强度随压应变的增大而增大，矫顽力随压应变的增大而减小。在拉伸应变下，NiFe纳米薄膜的饱和磁化强度随拉应变的增大而减小，矫顽力随拉应变的增大而增大，有效调控薄膜的磁学性能。弹性应变影响NiFe薄膜的电子结构，拉伸应变提高电子结合能，影响电子轨道磁矩和自旋磁矩，调控磁学性能。该研究为弹性应变调控薄膜的磁学性能提供新思路。