Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 13 of 13 for “"Nanostructured metals"”.
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A finite element model of grain boundary sliding for nanostructured metals
Nanocrystalline metals, i.e., polycrystalline metals with grain sizes in the nanometer range, have elicited significant interest recently due to their potential for achieving higher material strength in combination with increased formability at lower temperatures and higher strain rates, among …
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Quantifying the interface deformation mechanisms in nanostructured metals with atomic simulations and continuum field representations
Nanostructured metals possess ultra-high mechanical strength. A well-established consensus is that the deformation behaviors of these materials are governed by the extremely high density of interfaces. Previous studies have shown that, at nanoscale, interfaces act not only as obstacles of …
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Understanding the deformation mechanisms in nanostructured metals by a novel discrete crystal plasticity finite element model
<p>"Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. …
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Segregation and embrittlement in metallic interfaces : bounds, models, and trends
Metals with grain sizes below 100 nanometers exhibit remarkable hardness [1], wear resistance [2], and superplastic forming behavior [3], in addition to changes in many other properties. These materials are thus of technological interest as structural materials. However, the excess free energy …
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Cryomilling of Aluminum-based and Magnesium-based Metal Powders
… distances between different components. Nanostructured metals are of interest because of their unique physical and mechanical properties. The result of cryomilling is powder consisting of crystallites on the order of 30 – 50 nm. In order to characterize the properties of this material, it …
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Molecular-scale devices from first principles
… carbon-nanotube field effect transistors, and nanostructured metals or semiconductors. For such complex systems, characterizing the properties of the elementary building blocks becomes of fundamental importance. In this thesis we employ first-principles calculations based on density-functional …
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Quantitative Multispectral Biosensing and Imaging Using Plasmonic Crystals
… measurements. More recent work with nanostructured metals, such as nanohole arrays in gold films, enable sensing and imaging of surface binding events using simple, normal incident reflection or transmission configurations. These plasmonic structures exhibit multiple resonances that …
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Study of Field Enhancement by Spherical Voids in Gold Lattices by Using Three Dimensional Finite Difference Time Domain Simulations
… metal surface. Field enhancement properties of nanostructured metals can significantly enhance efficiency of an upconverter used in solar cells. The objective of this work was to develop an understanding why selfassembled porous and nanoporous spherical voids yield significantly higher field …
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Microstructural evolution and phase stability of Cu/Nb nanolaminates subjected to severe plastic deformation by high pressure torsion
Nanostructured metals and alloys have become attractive candidates for advanced material applications due to their potential to exhibit superior material properties, honed from the existence of large density of interfaces and their interactions with dislocations and defects. Severe plastic …
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Multiscale modeling of fracture and deformation in interface controlled materials
Many nanostructured metals are characterized by scale dependent mechanical properties and by size effects due to geometrical confinement. Dislocation activities, interface mediated plasticity, and macroscopic yielding are quite different from those in unconstrained metals. The role of interfaces …
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Microscale mechanical characterization of materials for extreme environments
Nanocrystalline metals are promising materials for applications that require outstanding strength and stability in extreme environments. Further improvements in the desirable mechanical properties of these materials require a better understanding of the relationship between their microstructure and …
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Understanding toughness and ductility in novel steels with mixed microstructures
… and ballistic performance in a class of nanostructured carbide-free bainite-austenite steels, sometimes known as ‘superbainite’. The mechanical properties of these alloys have been extensively reported, but their interpretation is not clear. The thesis begins with an introduction to both …
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Cryomilling and Spark Plasma Sintering of 2024 Aluminium Alloy
… in several fields. Bulk nanocrystalline metals and alloys can be produced by high energy milling of powders and their consolidation by sintering techniques characterized by a low thermal load in order to minimize grain growth. This is an alternative approach to other methods based on …