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چکیده
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In this study, NiTi thin films were deposited on the glass and NaCl substrates by means of magnetron sputtering method. The influence of aging temperature, over the range 300-500 o C, on phase transformation and mechanical properties of the sputtered NiTi thin films were studied by differential scanning calorimetry (DSC) and nano-indentation assay, respectively. The DSC curves showed that the aged specimens at 350, 400, and 500°C underwent two steps transformation during cooling process while a three steps transformation has been observed for the film aged at 450°C. This behavior clearly demonstrated the heterogeneity in chemical composition and microstructure of the sputtered thin film, which consequently resulted in the martensitic transformation of R and remained B2 to B19’ within two steps. According to nano-indentation analysis results, a peak point at aging temperature of 450°C is reached. The temperature hysteresis of all aged films was about 1°C, which can be considered as a positive sign for sensor application.
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