Effect of Scale on Structure and Strength of Layered

Nanoscale Multilayers 2013 18 An International Workshop on the Mechanical Behavior of Nanoscale Multilayers TUESDAY AM 10:40 AM Invited Nanoscale Colo...

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Effect of Scale on Structure and Strength of Layered Nanostructures in Deformed Metals

Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu Published in: Abstract book - Nanoscale Multilayers 2013

Publication date: 2013 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit

Citation (APA): Hansen, N., Zhang, X., & Huang, X. (2013). Effect of Scale on Structure and Strength of Layered Nanostructures in Deformed Metals. In Abstract book - Nanoscale Multilayers 2013 (pp. 18). Minerals, Metals & Materials Society, TMS.

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TUESDAY AM

Nanoscale Multilayers 2013 10:40 AM Invited Nanoscale Colour Control: Protective Decorative Coatings: Tomas Polcar1; 1Czech Technical University in Prague In this talk we present a new design of decorative tungsten oxide coatings. The coatings were deposited with a graded refractive index by magnetron sputtering with pulsing the reactive gas. The controlled injection of the reactive gas can produced a concentration profile gradient from pure tungsten to tungsten trioxide, determining the final apparent colour of the coating. A dynamic sputtering model was built to simulate the growth of the coating during the reactive gas pulsing which was validated by direct measurement of the oxygen gradient. Finally, these results were used for an optical model allowing the optical properties of the deposited tungsten oxide layer to be described. This procedure allows the deposition of coatings with the desired colour by using the models to select the optimal oxygen pulse parameters. Proposed method can be easily applied to almost any metal/metal-oxide system to produce selected gradients of oxides or nitrides at nanoscale. 11:00 AM Break

Session 2: Nanoscale Multilayers II Tuesday AM October 1, 2013

Room: Auditorium Location: IMDEA Materials Institute

Session Chair: Reinhold Dauskardt, Stanford University 11:30 AM Keynote Size Effects and Deformation Mechanisms in Metallic Multilayers: Ruth Schwaiger1; 1Karlsruhe Institute of Technology (KIT) The understanding of deformation of metallic multilayers has seen significant progress in the past decade. While nanoscale multilayers show great potential for high-strength applications, size-dependent deformation and predominant mechanisms are still under debate. Plastic deformation is governed by the constraint on dislocation motion but also strongly dependent on the interface structure between layers, which directly controls barrier strength and stability. Hindered dislocation motion inside small grains may make interfaces more active leading to interface-related deformation behaviors, e.g. grain rotation or grain boundary sliding typical of ultrafine grain sizes, possibly resulting in shear band formation. In this presentation, deformation behavior and size effects will be illustrated by means of two metallic multilayer systems with different combinations of microstructure length scale and interface structure (Cu/Au, Cu/Cr). The multilayers were investigated by indentation at different temperatures and insitu microcompression, both extremely useful methods for understanding mechanical behavior and deformation mechanisms of fine-grained structures. 12:10 PM Invited Anisotropy of the Mechanical Response of Al/SiC Multilayers: Javier Llorca1; Jon Molina-Aldareguia1; Saeid Lotfian1; Carl Mayer2; Nikhilesh Chawla2; Amit Misra3; 1IMDEA Materials Institute; 2Arizona State University; 3Los Alamos National Laboratory

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Nanoscale multilayers are potential candidates for applications that require materials operating in extreme environments, like in thermo-solar and/or nuclear energy technologies. In the case of metal-ceramic multilayers, the combination of metallic and ceramic layers at the nanoscale has demonstrated a good combination of strength and toughness. However, these materials are inherently anisotropic due to the layered structure; however, the anisotropic response is not well understood because the strength has been traditionally measured by nanoindentation techniques. In this talk, we address this issue by comparing the mechanical behavior of Al/SiC multilayers as a function of loading direction using two different techniques: nanoindentation and micropillar compression. The former can be carried out without intensive sample preparation but analysis of the results is difficult due to the complex stress state imposed by the indenter. The latter requires the use of complex micromachining techniques but the results are easier to interpret. 12:30 PM Invited Effect of Scale on Structure and Strength of Layered Nanostructures in Deformed Metals: Niels Hansen1; Xiaodan Zhang1; Xiaoxu Huang1; 1Technical University of Denmark Nanoscale multilayers in metals and alloys can be produced by various physical and chemical deposition techniques but they can also form by plastic deformation to large strain. The strengthening mechanisms are analyzed for two typical structures: (i) bulk structures with a layer thickness in the range 50 – 500 nm and (ii) surface structures with a layer thickness in the range 5 – 100 nm. The structural morphology and structural parameters are analyzed by various electron microscopy techniques. This microstructural analysis forms the basis for a discussion of strengthening mechanisms and strength-structure relationships at different length scale. Finally strength estimates are validated for bulk structures by tensile testing and for surface structures by hardness testing on the micro/nanometer scale. 12:50 PM Invited Mechancial Behavior of Preferred Interfaces in Bulk Multilayer Nanocomposites Produced via Accumulative Roll Bonding: Nathan Mara1; John Carpenter1; William Mook1; Weizhong Han1; Shijian Zheng1; Thomas Nizolek2; Jian Wang1; Thomas Wynn1; Irene Beyerlein1; 1Los Alamos National Laboratory; 2University of California, Santa Barbara In this presentation, we report on the plastic deformation mechanisms in Cu-Nb lamellar nanocomposites processed via Severe Plastic Deformation as a function of decreasing layer thickness. We utilize Accumulative Roll-Bonding (ARB) to process bulk Cu-Nb nanolamellar composites from 1 mm thick high-purity polycrystalline sheet down to layer thicknesses of 10 nm. This processing technique has the advantage of producing bulk quantities of nanocomposite material, and also exposes the interface and bulk constituents to large strains (1000’s of percent). These extreme strains result in rolling textures, interfacial defect structures, and deformation mechanisms very different from those seen in nanolamellar composites grown via Physical Vapor Deposition methods. For instance, deformation twinning is observed in Cu in ARB material as opposed to PVD material. Mechanical properties and behavior will be discussed in terms of the effects of interfacial content on deformation processes at diminishing length scales, and defect/interface interactions at the

An International Workshop on the Mechanical Behavior of Nanoscale Multilayers

Mechanical behavior of nanoscale multilayers, IMDEA, 1‐4 Oct., 2013  

Effect of scale on structure and strength of layered nanostructures in  deformed metals  Niels Hansen, Xiaodan Zhang and Xiaoxu Huang  Danish‐Chinese Center for Nanometals, Materials Science and Advanced Characterization  Section‐MAC, Department of Wind Energy, Risø Campus, Technical University of Denmark, DK‐ 4000 Roskilde, Denmark  Nanoscale  multilayers  in  metals  and  alloys  can  be  produced  by  various  physical  and  chemical  deposition  techniques  but  they  can  also  form  by  plastic  deformation  to  large  strain.  The  strengthening  mechanisms  are  analyzed  for  two  typical  structures:  (i)  bulk  structures  with  a  layer thickness in the range 50 – 500 nm and (ii) surface structures with a layer thickness in the  range 5 – 100 nm. The structural morphology and structural parameters are analyzed by various  electron microscopy techniques. This microstructural analysis forms the basis for a discussion of  strengthening mechanisms and strength‐structure relationships at different length scale. Finally  strength estimates are validated for bulk structures by tensile testing and for surface structures  by hardness testing on the micro/nanometer scale.  References  [1]  Hall–Petch  and  dislocation  strengthening  in  graded  nanostructured  steel.  Xiaodan  Zhang,  Niels Hansen, Yukui Gao, Xiaoxu Huang. Acta Materialia 2012; 60: 5933‐5943.