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

Abstract

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.