The Large Elastic Strain Of Nife Film On NiTi Shape Memory Alloy And The Regulation Of Magnetism&Adhesion Performance

Material's physicochemical performances is as a function of elastic strain(?_elastic),the elastic strain changes the interplanar spacing of the material and further changes the electronic structure of the atom,finally regulate mechanical,electrical,optical,magnetic properties,etc of the materials.Applying elastic strain methods traditionally,which need different substrates,the strain is small and is difficult to be controlled continuously;In addition,the method of applying an electric field is usually a"volatile"behavior,to a certain degree,which restrict materials applied in the field of non-volatile.This study chose NiTi-shape memory alloy?NiTi-SMA?as a substrate,prepared NiFe nanofilms on its surface with magnetron sputtering method,the magnetic and adhension performances of the films were controlled by different elastic strain?which root in the unique lattice shear deformation mechanism without dislocation glide of the NiTi base?.At the same time,the deformation behavior of NiFe nanofilms on the surface of metal Cu based on dislocation slip deformation mechanism was investigated.The microstructure of the films was studied by means of SEM,TEM and XRD firstly.It is found that the surface of the film was flat and continuous,which is FCC structure with a NiFe?111?-oriented growth.The NiFe/NiTiNb₁₀0 composite system were stretched with different strain,the diffraction peaks positions of the NiFe?111?were all shifted,indicating that the lattice shear deformation substrate can exert elastic strain on the film and the elastic tensile strain is up to 3.9%;The NiFe/Cu composite system were stretched with different strain,the diffraction peaks positions of NiFe?111?didn't move,which showed that the substrate Cu of dislocation slip deformation can't exert elastic strain on the film.The magnetic properties of the films with different elastic strain at 20nm thickness were investigated by using a vibrating sample magnetometer?VSM?.It is found that the coercive force and remanent magnetization of NiFe nanofilms were positively correlated with the applied tensile strain,while the saturation magnetization was negatively correlated with the applied tensile strain.By using X ray photoelectron spectroscopy?XPS?,studying the electronic structure of the NiFe film with different elastic strain at 10nm thickness by measuring the electron binding of energy surface elements.It's found that the peak positions of Fe2p and Ni2p were shifted in the direction of the large electron binding energy with the applied strain raising,indicating that the electronic structure near the interface of the composite system changed;The XPS depth profile of the sample with the same thickness of strain 9%showed that the Fe2p and Ni2p peaks also moved toward the direction of the large electron binding energy from the surface to the interior.This showed that the closer the base surface is,the larger the tensile strain?parallel to the axis?is.By measuring the contact angle take advantage of the contact angle admeasuring apparatus,and the corresponding surface energies are further calculated,the surface adhesion of the films were studied.It's noticed that the films we prepared are hydrophobic;The surface energy of all the thin films increases with the applied tensile strain increasing,which indicated that the adhesion properties of the films can be controlled effectively by the elastic strain.