Tailoring strength and plasticity of Ag/Nb nanolaminates via intrinsic microstructure and extrinsic dimension
Tailoring strength and plasticity of Ag/Nb nanolaminates via intrinsic microstructure and extrinsic dimension
复制标题
通过内在微观结构和外在尺寸调整Ag/Nb纳米层压材料的强度和塑性
DOI：
10.1016/j.ijplas.2018.09.012
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发表时间：
2019
影响因子：
9.8
通讯作者：
X.K. Meng
中科院分区：
文献类型：
--
作者：
Z.H. Cao;Y.P. Cai;C. Sun;Y.J. Ma;M.Z. Wei;Q. Li;H.M. Lu;H. Wang;X. Zhang;X.K. Meng
纳米层状金属复合材料的变形通常是通过从均匀变形到主要剪切带的过渡，随着层厚的减小，因此强度的提高往往牺牲材料的塑性。在这里，我们展示了两种方法来促进纳米层Ag/Nb柱的脆韧性转变。实际上，在保持柱直径不变的情况下，减小层厚可以提高多层复合材料的强度，抑制剪切破坏。此外，对于恒定的层厚度，减小柱直径抑制剪切带，并促进更均匀的塑性变形。此外，多层膜峰值强度时的临界层厚度随着柱直径的减小而单调增加。随着层厚的减小，界面结构由非晶层向共格界面演化。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。研究表明，内、外尺寸效应的共同作用可使合金在获得高强度的同时获得均匀变形。
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.