Characterization of Ni55.6Mn11.4Fe7.4Ga25.6 high temperature shape memory alloy thin film

The Ni55.6Mn11.4Fe7.4Ga25.6 high temperature shape memory alloy thin film was deposited onto silicon substrates by using radio-frequency (R.F.) magnetron sputtering technique. Surface morphology, crystallographic structure, martensitic transformation and microstructure were systematically investigated by means of scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that the film has columnar structure and an excellent surface quality. The film has seven-layered modulated orthorhombic structure with typical self-accommodated morphology at room temperature. The martensitic transformation start temperature of the film is up to 439 K, much higher than room temperature, displaying the promising application as high temperature actuator material.