Failure of metals III: Fracture and fatigue of nanostructured metallic materials
Failure of metals III: Fracture and fatigue of nanostructured metallic materials
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DOI：
10.1016/j.actamat.2015.07.049
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发表时间：
2016-04-01
期刊：
影响因子：
9.4
通讯作者：
Pardoen, Thomas
中科院分区：
文献类型：
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作者：
Pineau, Andre;Benzerga, A. Amine;Pardoen, Thomas
将金属合金的内部或外部尺寸推进到纳米尺度，可以产生坚固的材料，尽管大多数情况下是以低延展性和低抗裂性为代价的，对工程应用的转移产生负面影响。除了一些例外，这些特性在大块超细晶粒和纳米晶金属、纳米孪晶金属、基底上的薄金属涂层和独立的薄金属薄膜和纳米线中都可以观察到。本综述涵盖了所有这些系统，以揭示缺乏延展性和抗断裂性的根源，控制抗疲劳性的因素以及改善性能的方法的共性。在调查了各种加工方法和关键变形机制之后，我们系统地解决了三类系统在塑性局部化，损伤，静态和疲劳开裂方面的最新技术状况：(1)大块超细晶粒和纳米晶金属，(2)基片上的金属薄膜，以及(3)1D和2D独立微纳米级系统。在此过程中，我们的目标是促进薄膜力学、纳米力学、大块纳米晶金属和冶金学基础研究领域的进展相互促进，以增强高强度纳米结构系统的抗断裂和抗疲劳能力。这包括利用内在机制，例如，增强硬化和速率敏感性，以延迟颈缩，或提高晶界凝聚力，以抵抗晶间裂纹或空洞。外部方法也可以被利用，例如通过将金属与另一种材料杂化来使变形离域-就像在可拉伸电子中实践的那样。原则上，细化的组织可以改善疲劳裂纹的萌生，但代价是疲劳裂纹扩展速率增大。通过杂化的外部增韧可以阻止或桥接裂纹。内容和讨论基于最近文献的实验、理论和模拟结果，重点是将微观结构和物理机制与整体力学行为联系起来。(C) 2015材料学报Elsevier Ltd.出版。版权所有。
Pushing the internal or external dimensions of metallic alloys down to the nanometer scale gives rise to strong materials, though most often at the expense of a low ductility and a low resistance to cracking, with negative impact on the transfer to engineering applications. These characteristics are observed, with some exceptions, in bulk ultra-fine grained and nanocrystalline metals, nano-twinned metals, thin metallic coatings on substrates and freestanding thin metallic films and nanowires. This overview encompasses all these systems to reveal commonalities in the origins of the lack of ductility and fracture resistance, in factors governing fatigue resistance, and in ways to improve properties. After surveying the various processing methods and key deformation mechanisms, we systematically address the current state of the art in terms of plastic localization, damage, static and fatigue cracking, for three classes of systems: (1) bulk ultra-fine grained and nanocrystalline metals, (2) thin metallic films on substrates, and (3) 1D and 2D freestanding micro and nanoscale systems. In doing so, we aim to favour cross-fertilization between progress made in the fields of mechanics of thin films, nanomechanics, fundamental researches in bulk nanocrystalline metals and metallurgy to impart enhanced resistance to fracture and fatigue in high-strength nanostructured systems. This involves exploiting intrinsic mechanisms, e.g. to enhance hardening and rate-sensitivity so as to delay necking, or improve grain-boundary cohesion to resist intergranular cracks or voids. Extrinsic methods can also be utilized such as by hybridizing the metal with another material to delocalize the deformation - as practiced in stretchable electronics. Fatigue crack initiation is in principle improved by a fine structure, but at the expense of larger fatigue crack growth rates. Extrinsic toughening through hybridization allows arresting or bridging cracks. The content and discussions are based on experimental, theoretical and simulation results from the recent literature, and focus is laid on linking microstructure and physical mechanisins to the overall mechanical behavior. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.