The heating–cooling rate effect on thermal properties of high nickel-rich NiTi shape memory alloy.

In this study, the effects of heating and cooling rate on the thermal properties of high nickel-rich Ni55Ti45 shape memory alloy were investigated. Transformation temperatures and enthalpies were determined by differential scanning calorimetry. R-phase was observed with two-stage phase transformation during cooling. Transformation finish temperatures were affected, while the transformation start temperatures were not changed by heating–cooling rate. Kissinger, Takhor, and Ozawa methods were applied to find activation energy that is needed for phase transformation. The average activation energy value of 200.5 kJ mol−1 was calculated for Ni55Ti45 alloy. The calculated activation energy was found lower than the ones reported in the literature. [ABSTRACT FROM AUTHOR]