Large elastocaloric effect in Ti-Ni shape memory alloy below austenite finish temperature

Solid refrigeration technology based on the elastocaloric effect has a great potential alternative to the conventional vapor compression cooling. Here we report the large elastocaloric effect in Ti-Ni (50 at%) shape memory alloy below its austenite finish temperature A_f under different strain. Both Maxwell's and Clausius-Clapeyron equations are used to estimate the entropy change. The strain-induced entropy change increases with raising the strain and gets a maximum value at a few kelvins below A_f. The maximum entropy changes ΔS_max are -20.44 and -53.70 J/kg·K, respectively for 1% and 2% strain changes. Large entropy change may be obtained down to 20 K below A_f. The temperature of the maximum entropy change remains unchanged before the plastic deformation appears but moves towards low temperature when the plastic deformation happens.