  The NiTi shape memory alloy exhibited excellent superelastic property and
elastocaloric effect. Large temperature changes of 30 K upon loading and -19 K
upon unloading were obtained at room temperature, which were higher than those
of the other NiTi-based materials and among the highest values reported in the
elastocaloric materials. The asymmetry of the measured temperature changes
between loading and unloading process was ascribed to the friction dissipation.
The large temperature changes originated from the large entropy change during
the stress-induced martensite transformation (MT) and the reverse MT. A large
coefficient-of-performance of the material (COPmater) of 11.7 was obtained,
which decreased with increasing the applied strain. These results are very
attractive in the present solid-state cooling which is potential to replace the
vapor compression refrigeration technologies.
