Development of high-performance advanced elastocaloric materials is essential for the execution of elastocaloric refrigeration that can be an environment-friendly and high-efficiency substitute for the widely used traditional vapor-compression cooling technology. Here we have developed a bulk polycrystalline Ni-Ti-Cu-Co shape memory alloy exhibiting large elastocaloric effect, low stress hysteresis and room-temperature working temperature, all of which are of great importance to and urgently demanded for high-efficiency room-temperature elastocaloric refrigeration. This newly developed (Ni_42.5Ti₅₀Cu_7.5)₉₉Co₁ alloy shows a large room-temperature elastocaloric effect with directly measured adiabatic temperature change up to −14.4 K during unloading. The stress hysteresis of the isothermal superelastic stress-strain curve is as low as 60 MPa when the maximum tensile strain is 2.7%. Owing to the large elastocaloric effect and low stress hysteresis, a very high coefficient of performance up to 19 is achieved on the material level. This newly developed (Ni_42.5Ti₅₀Cu_7.5)₉₉Co₁ alloy is a robust candidate for efficient elastocaloric refrigeration. Advanced in-situ synchrotron high-energy X-ray diffraction technique was employed to reveal the phase transformation sequence and to accurately determine the crystal structure of different phases, based on which the lattice compatibility between the transforming phases was evaluated and the phase transformation strain was predicted, providing in-depth fundamental understanding of the martensitic transformation in this newly developed alloy. This work could be useful for designing high-performance elastocaloric materials for solid-state cooling applications.

高性能先进的弹性热材料的开发对于弹性热制冷的执行至关重要，它可以替代广泛使用的传统蒸气压缩冷却技术，是一种环保，高效的替代品。在这里，我们开发了一种具有大弹性效应，低应力滞后和室温工作温度的块状多晶Ni-Ti-Cu-Co形状记忆合金，这对于高效室温至关重要。弹性制冷。这种新开发的（Ni _42.5 Ti ₅₀ Cu _7.5）₉₉ Co ₁合金显示出很大的室温弹性热效应，在卸载过程中直接测量的绝热温度变化高达-14.4K。当最大拉伸应变为2.7％时，等温超弹性应力-应变曲线的应力滞回低至60 MPa。由于具有很大的弹性效应和低的应力滞后，因此在材料层面上可达到高达19的很高的性能系数。这种新开发的（Ni _42.5 Ti ₅₀ Cu _7.5）₉₉ Co ₁合金是有效弹性制冷的可靠选择。利用先进的原位同步加速器高能X射线衍射技术揭示相变序列并准确确定不同相的晶体结构，以此为基础，评估了相变之间的晶格相容性，并确定了相变应变。预言，对这种新开发的合金的马氏体相变提供了深入的基本了解。这项工作对于设计用于固态冷却应用的高性能弹性材料可能是有用的。