Elucidating the effect of local strain on the mechanical properties is of great significance for the design of high-performance layered metals. For this purpose, we conceived the present study, featured by tailoring the local strain by layer thickness design, and simultaneous monitoring of local strain and geometrically necessary dislocations (GNDs) via coupling electron backscatter diffraction (EBSD) and high-resolution digital image correlation (DIC). In addition, synchrotron X-ray micro-computed tomography (μCT) was employed to analyze the microcracks that serve as another form of strain localization. Such detailed experimental studies revealed that the interfacial strain gradient was rapidly elevated, and the strain localization band was effectively dispersed as the layer thickness decreased. This leads to two typical transitions, from grain-boundary-related to layer-interface-related plastic deformation mode, and from macroscopic shear to zig-zag fracture mode. Their influences on the mechanical properties, as well as underlying mechanisms, were discussed based on the relationship among the layer thickness, strain gradient, strain localization, GND density, and microcracks. Our work not only contributes to the fundamental understanding of the mechanical behavior of multilayered metals but also offers guidance for the structural design of high-performance metals aimed at achieving superior strength-ductility combinations.

中文翻译：

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局部应变对异质多层铝塑性变形和断裂机制的影响


阐明局部应变对力学性能的影响对于高性能层状金属的设计具有重要意义。为此，我们构思了本研究，其特点是通过层厚度设计来定制局部应变，并通过耦合电子背散射衍射（EBSD）和高分辨率数字图像相关性同时监测局部应变和几何必要位错（GND）。 DIC）。此外，还采用同步加速器 X 射线微计算机断层扫描 (μCT) 来分析作为另一种形式的应变定位的微裂纹。这些详细的实验研究表明，随着层厚度的减小，界面应变梯度迅速升高，应变局部化带有效地分散。这导致了两种典型的转变，从晶界相关到层界面相关塑性变形模式，以及从宏观剪切到锯齿形断裂模式。基于层厚度、应变梯度、应变局部化、GND 密度和微裂纹之间的关系，讨论了它们对机械性能的影响以及潜在机制。我们的工作不仅有助于对多层金属的机械行为的基本理解，而且还为旨在实现卓越的强度-延展性组合的高性能金属的结构设计提供指导。