Double domes of mesoscopic localized anisotropic lattice strain in HCP-Ag₇₅Al₂₅ under high pressure

In this research, we report a new discovery of anomalous localized anisotropic lattice strain under uniaxial non-hydrostatic pressure to 40 GPa studied with micro-focused synchrotron X-ray diffraction. With experiments on our synthesized nanocrystalline granular material, a phase-stable HCP-Ag₇₅Al₂₅ alloy, the analyzed results show direct evidence that reaching a critical value of localized anisotropy in the lattice strain leads to grain fracture. This discovery of the evolution in such anomalous anisotropic strain further reveals the link between micro- and macroscopic anisotropic mechanical behaviors of granular materials through a mesoscopic way and may set a reference for further studies on materials anisotropy or designing new materials with specific anisotropic mechanical properties.本研究报道了一项新发现：在高达40 GPa的单轴非静水压条件下，借助微聚焦同步辐射X射线衍射（micro-focused synchrotron X-ray diffraction）技术观测到异常局域各向异性晶格应变。本研究针对合成的纳米晶颗粒材料——相稳定的六方密排（HCP）Ag₇₅Al₂₅合金开展实验，分析结果直接证实：当晶格应变的局域各向异性达到临界阈值时，会引发晶粒断裂。此项关于异常各向异性应变演化的发现，通过介观尺度的研究视角进一步揭示了颗粒材料微观与宏观各向异性力学行为之间的关联，可为后续材料各向异性研究或具备特定各向异性力学性能的新型材料设计提供参考依据。