Investigation of the elastocaloric effect in laser powder bed fusion NiTi structures

The endothermic reversible martensitic phase change in NiTi has the potential to be used for refrigeration. How-ever, to have high efficiency in the elastocaloric effect, NiTi materials with a large surface area are required. In this study, for the first time, the porous structures have been successfully introduced to the field of elastocaloric effect to boost efficiency by enhancing the area in contact with the ambient and reducing the load required to trigger the elastocaloric materials. NiTi porous structures named diamond, gyroid, and primitive, fabricated by the laser powder bed fusion (LPBF) technique, were tested experimentally to determine the magnitude of temper-ature change using an infrared radiation camera during uniaxial compression testing. The characterization of the microstructure, phase transformation analysis, strain distribution, and temperature fields of porous materials are explored. The diamond sample with adiabatic temperature changes as high as 5.31 & DEG;C has a better elastocaloric effect compared to the others. However, there has been a very inhomogeneous martensite phase change inside the samples, limiting the elastocaloric effect of porous structures.