An overview of interface-dominated deformation mechanisms in metallic nanocomposites elucidated using in situ straining
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An overview of interface-dominated deformation mechanisms in metallic nanocomposites elucidated using in situ straining in a TEM Yuchi Cui1,a), Nan Li2,b), Amit Misra3 1
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 3 Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA; and Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA a) Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/editor-manuscripts/. This paper has been selected as an Invited Feature Paper. 2
Received: 22 November 2018; accepted: 28 January 2019
Nanostructured multiphase metallic materials present extraordinary properties, such as high strength, enhanced fatigue and radiation resistance, and thermal stability, compared to conventional bulk metallic materials. Previous research studies have shown that their deformation and fracture behavior are dominated by defect interactions at internal interfaces. In situ straining, including nanoindentation, compression, and tension, in a transmission electron microscope (TEM) has emerged as a powerful tool to investigate the physics of defect– interface interactions at the nano-scale and even atomic scale. The mechanistic insights gained from these experiments coupled with dislocation theory and atomistic modeling has helped develop a fundamental understanding of the mechanical properties. In this article, through some recent investigations on observing dislocation and interface activities, crack propagation, and nanopillar compression, we present current progress in utilizing in situ TEM straining to examine interface-dominated deformation mechanisms.
Introduction Nanostructured multi-phase metallic materials, which are composed of two or more metals with feature sizes in the range of a few nanometers to a few tens of nanometers, present significant advantages over conventional bulk materials, including high flow strengths approaching 1/2 to 1/3 of the theoretical limit (of the order of l/30 where l is the shear modulus) [1, 2], enhanced fatigue and radiation damage tolerance [3, 4], and thermal stability [5]. Examples of model systems include (but are not limited to) Cu–Nb, Al–Nb, Cu–Ag, and Cu–Mo with nanolaminate or bicontinuous, intertwined morphologies and are referred to as metallic nano-composites (MNCs) in the remainder of this article. Extensive research has been conducted to understand the deformation mechanisms in the MNCs, and it was found that the key factors that influence the mechanical properties of an MNC include interface crystallinity; feature size, which can be
ª Materials Research Society 2019
defined as the average spacing b
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