Study of the elastocaloric effect and mechanical behavior for the NiTi shape memory alloys

TL;DR

This study investigates the elastocaloric effect and mechanical behavior of NiTi shape memory alloys, revealing significant temperature changes and high efficiency, indicating potential for solid-state cooling applications.

Contribution

The paper provides detailed analysis of the elastocaloric effect in NiTi alloys, highlighting their superior temperature change and efficiency compared to other materials.

Findings

Temperature change of 30 K upon loading and -19 K upon unloading.

High coefficient-of-performance (COP) of 11.7.

Asymmetry in temperature change due to friction dissipation.

Abstract

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.