Giant elastocaloric temperature change and its cyclic stability in [001]-oriented Cu71Al17.5Mn11.5 single crystal

Environmentally friendly and energy-efficient elastocaloric cooling is a promising alternative to conventional vapor-compression technology. In this work, we observed a large superelastic strain of 9.4 % and a giant adiabatic temperature change (ΔT_ad) of 19.5 K in [001]-oriented Cu₇₁Al_17.5Mn_11.5 single crystals. The present ΔT_ad breaks the record in Cu-based elastocaloric alloys. As revealed using in-situ digital imaging correlation (DIC) technique, the uniaxial stress along the [001] direction promoted two martensitic correspondent variant pairs, leading to the non-uniform strain distribution and pronounced stress hysteresis. Upon 10⁴ cycles, the ΔT_ad degraded from 19.5 to 2.1 K, with a cyclic degradation rate of 1.7 × 10⁻³ K per cycle. Our study provides valuable insights into the selection of crystallographic orientation and fatigue resistance strategy for Cu-based elastocaloric alloys.