Constrained thermoelastic martensitic transformation studied by modulated DSC

The constrained thermoelastic martensitic transformation of TiNiCu wires embedded in an epoxy matrix was studied by modulated differential scanning calorimetry (MDSC). Results showed that the non-reversing heat flow (NHF) signal of TiNiCu wires in a free condition is quite small whether the wires are pre-strained or not, while the NHF signal of the TiNiCu wires embedded in the epoxy matrix increases significantly with increasing level of pre-strain. Analysis showed that this significant increase of the NHF value is related to a term which is a function of the stress rate (dσ/dT). If the interface is perfectly bonded, this term contributes to the reversing heat flow (RHF) signal, while if the interface is debonded, this term contributes to the NHF signal.