Anomalous internal friction associated with the thermoelastic martensitic transformation in a Cu-Al-Ni-Mn-Ti alloy

An anomalous internal friction phenomenon was observed during the reverse martensitic transformation of a polycrystalline Cu-Al-Ni-Mn-Ti shape memory alloy, i.e. negative internal friction appeared during the transformation, when frequency is relatively low due to the interaction between the martensitic variants with positive and negative loss elastic modulus. The latter can be stabilized by applied stress when their orientation is unfavorable for the applied stress because of the constraint of austenite in a single growth direction.