Abstract Nanolayered metallic composites usually deform via a transition from homogeneous deformation to major shear banding with decreasing layer thickness, and thus the improvement of strength often sacrifices the plasticity of materials. Here, we show two methods to promote brittle-to-ductile transition in nanolayered Ag/Nb pillars. Intrinsically, while keeping the pillar diameter constant, the reduction of layer thickness can increase the strength of multilayers and suppress shear induced failure. Extrinsically, for a constant layer thickness, decreasing the diameter of pillar suppresses shear bands and promotes more uniform plastic deformation. Furthermore, the critical layer thickness at peak strength of multilayers increases monotonically with decreasing pillar diameter. Interface structures evolve from amorphous layer to coherent interface with reduction of layer thickness. Homogeneous co-deformation mediated by heterogeneous interfaces and columnar grain boundaries promotes a unique work hardening behavior. This study indicates that a combination of intrinsic and extrinsic size effect may enable the accomplishment of high strength and uniform deformation simultaneously.

中文翻译：

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通过内在微观结构和外在尺寸调整 Ag/Nb 纳米层压板的强度和塑性

摘要 纳米层状金属复合材料通常通过从均匀变形到主剪切带的过渡而随着层厚度的减小而变形，因此强度的提高往往会牺牲材料的塑性。在这里，我们展示了两种方法来促进纳米层 Ag/Nb 柱中的脆性到韧性转变。从本质上讲，在保持柱直径不变的同时，层厚的减少可以增加多层的强度并抑制剪切引起的失效。从本质上讲，对于恒定的层厚，减小柱子的直径会抑制剪切带并促进更均匀的塑性变形。此外，多层峰值强度处的临界层厚度随着柱直径的减小而单调增加。随着层厚度的减少，界面结构从非晶层演变为相干界面。由异质界面和柱状晶界介导的均匀共变形促进了独特的加工硬化行为。该研究表明，内在和外在尺寸效应的结合可以同时实现高强度和均匀变形。