Enhanced the superelasticity and elastocaloric cooling effect of NiTi alloy treated shot peening

In this work, a method to enhance the superelasticity and elastocaloric cooling effect of NiTi alloy by shot peening treatment was proposed. This work investigated the influence of shot peening on the microstructure of NiTi alloy, focusing on deformation modes (uniform and non-uniform), superelasticity and elastocaloric cooling effect during stress-cycling-induced phase transformation. The results demonstrated that shot peening significantly altered the microstructure of the samples, changing it from a fully austenitic state to a “sandwich” structure. This newly formed microstructure consists of needle-like martensite near the surface, austenite in the middle layer, and plate-like martensite at the core. Furthermore, shot peening effectively mitigated non-uniform deformation during phase transformation, resulting in reduced local strain concentrations and temperature inhomogeneity. This process also minimized the degradation of superelasticity and the elastocaloric cooling effect, thereby enhancing the cyclic stability of these properties. •A method to enhance the superelasticity and elastocaloric cooling (EC) effect of NiTi by Shot Peening (SP) was proposed.•SP mitigated non-uniform deformation, resulting in reduced local strain concentrations and temperature inhomogeneity.•SP minimized the degradation of superelasticity and the EC effect, thereby enhancing their cyclic stability.