Phase transition and mechanical damping properties: A DMTA study of NiTiCu shape memory alloys

Internal friction measurement is a well-known investigation technique of the damping property of shape memory alloys (SMAs). It has already been demonstrated that this practice conducted in temperature scanning at a constant solicitation frequency is also useful in determining the path of the martensitic transformation and also the influence of hydrogen content on the martensitic properties. There is indeed a lack of studies about SMA internal friction as a function of solicitation frequency; systematic and rigorous analysis has not been reported yet. In this work the path of the martensitic transformation of Ni50−xTiCux alloys (x = 3–10at%) is investigated through Dynamic Mechanical Thermal Analysis (DMTA): internal friction as a function of temperature at a constant flexural frequency and internal friction as a function of flexural frequency at a constant temperature were evaluated. Results show that the two scans are both sensitive to phase transitions and microstructural changes. ► T-scan internal friction measure shows the orthorhombic structure at x = 6at%. ▶ T-scan internal friction measure is more sensitive as respect to thermal analysis. ▶ F-scan internal friction measure is a new probe in the study of phase transition.