Shape‐memory alloys (SMAs) are the most stretchable metallic materials thanks to their superelastic behavior associated with the stress‐induced martensitic transformation. This property makes SMAs of potential interest for flexible and wearable electronic technologies, provided that their properties will be retained at small scale. Nanocompression experiments on Cu‐Al‐Be SMA single crystals demonstrate that micro‐ and nanopillars, between 2 µm and 260 nm in diameter, exhibit a reproducible superelastic behavior fully recoverable up to 8% strain, even at the nanoscale. Additionally, these micro‐/nanopillars exhibit a size effect on the critical stress for superelasticity, which dramatically increases for pillars smaller than ≈1 µm in diameter, scaling with a power law of exponent n = −2. The observed size effect agrees with a theoretical model of homogeneous nucleation of martensite at small scale and the universality of this scaling power law for Cu‐based SMAs is proposed. These results open new directions for using SMAs as stretchable conductors and actuating devices in flexible and wearable technologies.

中文翻译：

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关于纳米尺度上超弹性尺寸影响的通用尺度定律促进了形状记忆合金在可拉伸装置中的使用

形状记忆合金（SMA）是最易拉伸的金属材料，这归因于其与应力诱发的马氏体转变相关的超弹性行为。该特性使SMA对于柔性和可穿戴电子技术具有潜在的吸引力，但前提是它们的特性将在小范围内保留。在Cu-Al-Be SMA单晶上进行的纳米压缩实验表明，直径在2 µm至260 nm之间的微柱和纳米柱具有可再现的超弹性行为，即使在纳米级，也可以完全恢复到8％的应变。此外，这些微/纳米柱对超弹性的临界应力表现出尺寸效应，当直径小于≈1µm的柱子时，应力会显着增大，并随幂指数n的变化而变化。= -2。观察到的尺寸效应与小尺寸马氏体均匀成核的理论模型相一致，并提出了这种基于铜基SMA的定标幂定律的普遍性。这些结果为在柔性和可穿戴技术中将SMA用作可拉伸导体和驱动装置开辟了新的方向。