Measurement of specific heat, latent heat and phase transformation temperatures of shape memory alloys
Guanghan Wang, Xin Xiang Jiang and Darius Nikanpour
Applications using shape memory alloy (SMA) require reliable techniques to model such macro-mechanical phenomena to predict the strongly-coupled thermal and mechanical performances, so as to integrate SMA actuator into the specific designs. However, less attention has been paid to those properties as a comparison to the mechanical properties, which has limited the development of reliable engineering models to predict the thermo-mechanical phenomena when phase transformations occur. In this work, the specific heat of NiTi SMA materials is measured over wide temperature ranges using the Differential Scanning Calorimeter (DSC) technique in different devices. The start and finish temperatures and latent heat of the phase transformations are determined from the measured specific heat. Concepts of the “thermodynamic temperature phase transformation” and the “nominal temperature phase transformation” are introduced. And finally a comparison is made between the current method and the “traditional” heat flow method of DSC.