A Perspective on Elastocaloric Effect in Ti-Ni-Based Shape Memory Alloys

Elastocaloric cooling utilizes in a cyclic manner the latent heat of the stress-induced transformation, which sets challenges for the fatigue endurance and performance of elastocaloric materials. Ti-Ni-based alloys are widely studied and presently the most frequently used shape-memory alloy group and they have attracted wide research interest in the elastocaloric aspect. The latent heat caused by stress-induced B2-B19 ' martensite transformation has been frequently applied for the elastocaloric use, and large adiabatic temperature changes have been reported. Despite the high latent heat associated to B2-B19 ' phase transformation, the fatigue properties have not been satisfactory. Stress-induced B2-R transformation of Ni-Ti-based alloys is interesting in this respect, since it has a low hysteresis but yet relatively high latent heat. In this short review, we give a brief insight to the Ti-Ni-based shape memory alloys from the elastocaloric point of view.