Shape memory alloys (SMAs) hold great promise for phase-change-based energy storage, demanding attainment of both large thermal hysteresis and good thermal cyclic stability. Nevertheless, these two properties are often mutually exclusive. Here, we developed a multicomponent TiHfZrNi alloy that exhibits a large hysteresis of 44.6 °C and a small transformation temperature shift of 0.5 °C after 20 thermal cycles. This performance is superior for applications in thermal management, surpassing most TiNi-based SMAs. The presence of Hf and Zr atoms with a larger size increases the lattice mismatch between the austenite and martensite phases, thereby enlarging the thermal hysteresis. Simultaneously, these atoms tend to form heterogeneous lattice strains and chemical short-range order, strengthening the matrix. As a result, fewer defects accumulate during thermal cycling, leading to good thermal cyclic stability. Multicomponent high-entropy SMAs provide an alternative approach to balancing conflicting properties such as large thermal hysteresis and good thermal cyclic stability.

中文翻译：

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多元 TiHfZrNi 合金具有大的热滞后和良好的热循环稳定性


形状记忆合金（SMA）在基于相变的能量存储方面具有广阔的前景，要求同时实现大的热滞后和良好的热循环稳定性。然而，这两个属性常常是相互排斥的。在这里，我们开发了一种多组分 TiHfZrNi 合金，在 20 次热循环后，该合金表现出 44.6 °C 的大滞后和 0.5 °C 的小转变温度变化。这种性能对于热管理应用来说非常优越，超过了大多数基于 TiNi 的 SMA。较大尺寸的Hf和Zr原子的存在增加了奥氏体相和马氏体相之间的晶格失配，从而增大了热滞后。同时，这些原子往往会形成异质晶格应变和化学短程有序，从而强化基体。因此，热循环过程中积累的缺陷较少，从而具有良好的热循环稳定性。多组分高熵 SMA 提供了另一种方法来平衡相互冲突的特性，例如大的热滞后和良好的热循环稳定性。