Long-Term Stable Elastocaloric Effect in a Heusler-Type Co₅₁V₃₃Ga₁₆ Polycrystalline Alloy

Abstract

Cyclic stability is of utmost importance for the long-term work of caloric materials in solid-state refrigeration. Heusler-type shape memory alloys show a large elastocaloric effect under low driving stress, but their intrinsic brittleness always leads to poor cyclic stability. Here, we demonstrate the simultaneously achieved large elastocaloric effect and long-term cyclic stability in a Heusler-type Co 51 V 33 Ga 16 polycrystalline alloy. Over a wide temperature range of 290−340 K, large adiabatic temperature change (ΔT ad ) values of −6.0 to −10.9 K can be obtained upon fast unloading. Moreover, by synthetically considering the influences of deformation parameters on the ΔT ad values, stress hysteresis, energy dissipation, and temporary residual strain to balance cooling capacity and cyclability, large ΔT ad values higher than 6.0 K are maintained for more than 50 000 superelastic cycles performed under the compressive strain of 3.5% and strain rate of 1.1 × 10 −2 s −1 , showing a very low degradation rate of 2 × 10 −5 K per cycle. Such cyclic stability of elastocaloric effect well outperforms those reported in Heusler-type alloys so far.