The maximum recoverable strain of most crystalline solids is less than 1% because plastic deformation or fracture usually occurs at a small strain. In this work, we show that a SrNi₂P₂ micropillar exhibits pseudoelasticity with a large maximum recoverable strain of ∼14% under uniaxial compression via unique reversible structural transformation, double lattice collapse–expansion that is repeatable under cyclic loading. Its high yield strength (∼3.8 ± 0.5 GPa) and large maximum recoverable strain bring out the ultrahigh modulus of resilience (∼146 ± 19 MJ/m³), a few orders of magnitude higher than that of most engineering materials. The double lattice collapse–expansion mechanism shows stress–strain behaviors similar to that of conventional shape-memory alloys, such as hysteresis and thermo-mechanical actuation, even though the structural changes involved are completely different. Our work suggests that the discovery of a new class of high-performance ThCr₂Si₂-structured materials will open new research opportunities in the field of pseudoelasticity.

中文翻译：

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SrNi2P2微柱通过双晶格塌缩和膨胀的伪弹性

大多数结晶固体的最大可恢复应变小于 1%，因为塑性变形或断裂通常发生在很小的应变下。在这项工作中，我们展示了 SrNi ₂ P ₂微柱通过独特的可逆结构转变、在循环载荷下可重复的双晶格坍塌-膨胀，在单轴压缩下表现出伪弹性，最大可恢复应变约为 14%。其高屈服强度 (∼3.8 ± 0.5 GPa) 和大的最大可恢复应变带来超高的回弹性模量 (∼146 ± 19 MJ/m ³)，比大多数工程材料高几个数量级。双晶格坍缩-膨胀机制显示出类似于传统形状记忆合金的应力-应变行为，例如滞后和热机械驱动，即使所涉及的结构变化完全不同。我们的工作表明，新型高性能 ThCr ₂ Si ₂结构材料的发现将为伪弹性领域开辟新的研究机会。