Preparation And Characterization Of The Composite With Discontinuous NiTi SMA Thin Film

The NiTi SMA thin film with discontinuous distribution was deposited on the PZT substrates by magnetron sputtering method with the die. Phase composition, microstructural characteristics and composition distribution of the NiTi SMA /PZT sample have been examined by using X-ray diffraction (XRD) , scanning electron microscope (SEM) and energy dispersive X-ray spectrometer(EDS). Binding force between NiTi SMA film and PZT substrate has been tested by using microhardness tester, fracture toughness has been tested by using vickers and damping capacity has been tested by using dynamic elastic modulus instrument. Dielectric properties have been tested by using ZJ-3A quasi-static instrument and Automatic LCR Meter 4225.The results show that after crystallization treatment at 600℃, we obtain crystal NiTi SMA /PZT composite sample with compact equiaxed crystal microstructure and little defects, bisides that the chemical binding is formed between the NiTi SMA thin film and PZT substrate, so the binding force and fracture toughness of the sample with discontinuous distribution NiTi SMA thin film improve more than the sample with continuous distribution NiTi SMA thin film by 6.8% and double above ; Because of the two-dimensional constraint by NiTi SMA thin film to PZT substrate, a platform which represents the stable region for damping of the sample with continuous distribution NiTi SMA thin film appeares on the damping curve of the sample ; The phenomenon of ion relaxation polarization happen easily because of the interaction force between the discontinuous NiTi SMA thin film and PZT substrate is less than that between the continuous NiTi SMA thin film and PZT substrate, so the dielectric constant of the sample with discontinuous distribution NiTi SMA thin film is higher than the sample with continuous distribution NiTi SMA thin film by 11%; Because the volume of the discontinuous NiTi SMA thin film and the interaction force between the NiTi SMA thin film and PZT substrate are all less than that of the continuous NiTi SMA thin film , so external force suffered by the sample and the electric displacement in the PZT substrate are weaker.Due to the above reasons, the piezoelectric constant of the sample with discontinuous distribution NiTi SMA thin film is higher than the sample with continuous distribution NiTi SMA thin film by 2.8%.