Large elastocaloric effect in Ti–Ni shape memory alloy below austenite finish temperature**Project supported by the National Natural Science Foundation of China (Grant Nos. 51671192 and 51531008) and the Chinese Academy of Sciences (Grant No. KJZD-EW-M05).

Abstract

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 Af 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 Af. The maximum entropy changes ΔSmax 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 Af. The temperature of the maximum entropy change remains unchanged before the plastic deformation appears but moves towards low temperature when the plastic deformation happens.