Non-Conventional Techniques for the Study of Shape Memory Alloy Phase Transitions

Differential scanning calorimetry and electrical resistance measurements are the two most common techniques for the study of phase transition path and temperatures in shape memory alloys (SMA) in stress-free condition. Besides, it is well known that internal friction measurements as a function of temperature at a constant stress frequency are also useful for this purpose. There are indeed some further techniques which are seldom used for the characterization of SMA transition: internal friction as a function of stress frequency at a constant temperature, coefficient of thermal expansion and magnetic measurements. In this work we discuss the potentiality of these non-conventional techniques for the study of SMA phase transition. Measurements were conducted on several fully annealed NiTiCu samples ranging from 3 to 10 at% in Cu content. Results show that all these unusual techniques provide significant information about the existence of intermediate phases and give similar information about phase transformation temperatures.