Topology-dependent scaling laws for the stiffness and strength of nanoporous gold
Topology-dependent scaling laws for the stiffness and strength of nanoporous gold
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DOI：
10.1016/j.actamat.2016.08.012
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发表时间：
2016-10-15
期刊：
影响因子：
9.4
通讯作者：
Volkert, C. A.
中科院分区：
文献类型：
--
作者：
Mangipudi, K. R.;Epler, E.;Volkert, C. A.
纳米多孔金（np-Au）与大孔金的不同之处在于它的韧带和孔长尺度，它的高相对密度，以及它非常独特的中尺度细胞结构。当重新审视传统的大孔泡沫缩放定律的适用性，以np-Au，困难不仅存在于确定纳米韧带的固体性质，而且因为np-Au结构是不自相似的相对密度的变化。因此，需要明确区分相对密度和结构的影响。本文旨在通过比较真实的np-Au结构的整体机械响应与旋节结构和螺旋结构的行为，来捕获拓扑结构和形态学在标度律中的作用。这些结构的定量形态和拓扑表征已经进行了研究，并使用有限元（FE）模拟的宏观弹塑性响应的np-Au的作用。通过有限元模拟得到的真实的np-Au结构的弹性模量预测值与纳米压痕测量值吻合较好，验证了数值模拟的正确性。定量结构分析表明，np-Au和spinodal结构的拓扑结构是非常不同的，但在他们的形态相似。另一方面，旋螺在形态和拓扑上都与np-Au非常不同。结果表明，宏观刚度和强度是高度敏感的拓扑结构，而相对较不敏感的形态。结构拓扑结构的影响被捕获到修改后的比例律的刚度和强度的几何前因子被发现随缩放的属线性变化。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Nanoporous gold (np-Au) differs from its macroporous counterparts through its ligament and pore length scales, its high relative density, and its very distinct mesoscale cellular architecture. When reexamining the applicability of conventional macroporous foam scaling laws to np-Au, difficulties persist not only in determining the solid properties of nanoscale ligaments, but also because np-Au structure is not self-similar as the relative density changes. Thus, a clear distinction of the effects of relative density and structure is required. This paper aims to capture the role of topology and morphology into the scaling laws by comparing the overall mechanical response of real np-Au structures with the behavior of spinodal and gyroid structures. Quantitative morphological and topological characterization of these structures has been carried out and their role on the macroscopic elastoplastic response of np-Au has been studied using finite element (FE) simulations. The predicted elastic modulus of real np-Au structures from FE simulations is in remarkable agreement with the nanoindentation measurements, and validates the numerical simulations. Quantitative structural analysis reveals that np-Au and spinodal structures are topologically very distinct, but similar in their morphology. On the other hand, gyroids are both morphologically and topologically very distinct from np-Au. The results suggest that the macroscopic stiffness and strength are highly sensitive to the topology, while being relatively much less sensitive to the morphology. The effects of structural topology are captured into modified scaling laws where the geometric pre-factors for the stiffness and strength are found to vary linearly with the scaled genus. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.