For NiTiCu SMA we find their phase transformation curves are visible between 20-100 degrees and at times it's visible between 250-400 degrees for the same samples. Any specific reason behind this variation?
There is no reason for this kind of fluctuations, particularly in TiNiCu in which the transformations temperatures are limited to below 100ºC. In other alloy systems (Cu-based) martensite stabilization processes can produce this kind of fluctuations during the reverse transformation, but this kind of processes have not been reported in TiNiCu.
Please check carefully the measurement system of your DSC, or (excuse me for giving you this advice) chek that the plotted temperature is always in degrees celsius, or eventually the scale for plotting the results is in Kelvin (eventually somebody has changed the scale on your DSC from Celsius to Kelvin without notice).
I hope that this could be useful for your next measurements.
Thank you so much for your valuable suggestions Il check the factors you have mentioned. Thank you again.
To Dr. Jose San Juan :
Respected Sir,
Thank you so much for your valuable suggestions. Your point is right even some minor manual errors can harm the results of the experiment and I agree it. So as you have suggested il make sure that the experiments are repeated without any such flaws. Thank you again.
First, check that this is not an experimental artifact. Second, sample history plays a crucial role in response of system in case of first order transition.