Isothermal High Damping in Shape Memory Alloys

Shape memory alloys are often considered as high damping materials. In fact, internal friction spectra measured at a fixed frequency (1 Hz for instance) during a temperature change, exhibit a very large damping effect linked to the forward or reverse phase transformations. This effect increases with the temperature change rate and decreases with the measurement frequency. If the temperature is stabilized at the maximum of the effect, the damping drops very quickly to a very low value. However, in some cases, high damping can be evidenced in these materials at very low frequency during isothermal experiments.