AI 中文总结
本研究利用原子探针层析技术，揭示亚稳态Ag₂₄Au₂₀Pd₅₀Pt₆电催化剂中隐藏的低温相演化路径，发现富Pt相转变伴随析氢活性下降3.7倍，为成分复杂材料设计提供新变量。
AI 中文摘要
大多数成分复杂材料（CCMs，常称为高熵合金）处于亚稳态，其优异性能往往属于动力学捕获状态。然而，决定长期稳定性的低自由能相态转变路径可能被隐藏，因为扩散控制的原子再分配速度过慢，无法在实验可及的时间尺度上被观测到。这一盲区在CCMs设计中尤为突出：人们会对巨大的成分空间进行性能筛选，但材料选择时很少考虑决定性能能否持续的低温动力学及相关转变路径。本研究中，我们利用富含缺陷的纳米级体积结合原子探针层析技术，无需依靠高温加速转变，即可观测并重构亚稳态Ag₂₄Au₂₀Pd₅₀Pt₆电催化剂中隐藏的相演化路径。通过改变微观结构起始状态、退火温度和时间，我们发现面心立方（fcc）基体中会析出富Pt相，随后发生粗化并重新均匀化；富Pt相在均匀化后会以延迟的动力学可及性再次出现，延长退火时间可将该路径拓展至300℃。原子级模拟也独立预测了相同的富Pt相选择。该转变伴随析氢催化活性下降3.7倍。这些结果确立了隐藏相演化路径作为材料设计的一个变量：解析这些路径不仅可指导基于合成态性能的亚稳态CCMs选择，还能指导基于其随时间可达到的相态及相关功能的选择。
英文摘要
Most compositionally complex materials (CCMs, frequently referred to as high entropy alloys) are metastable and their attractive properties often belong to kinetically trapped states. However, pathways towards lower-free-energy phase states governing long-term stability, can remain hidden because diffusion-controlled atomic redistribution is too slow to be revealed at experimentally accessible timescales. This blind spot is acute in CCM design: enormous compositional spaces are screened for performance, yet the low-temperature kinetics and the associated transformation pathways determining whether that performance persists are rarely considered in material selection. Here we use defect-rich nanoscale volumes coupled with atom-probe tomography to access and reconstruct the hidden phase-evolution pathway in a metastable Ag24Au20Pd50Pt6 electrocatalyst, without relying on elevated temperatures to accelerate the transformation. By varying microstructural starting state, annealing temperature and time, we reveal precipitation of a Pt-rich phase within the fcc matrix, its coarsening and re-homogenization. The Pt-rich phase recurs after homogenization with delayed kinetic accessibility, while prolonged annealing extends the pathway to 300°C. Atomistic simulations independently predict the same Pt-rich phase selection. The transformation is accompanied by a 3.7-fold loss of catalytic activity for hydrogen evolution. These results establish hidden phase-evolution pathways as a materials-design variable: resolving them can guide the selection of metastable CCMs not only for their as-synthesized properties, but also for the phase states and associated functionalities they may access over time.
