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Добірка наукової літератури з теми "Nanocrystalline copper"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

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Статті в журналах з теми "Nanocrystalline copper"

Bazios, Panagiotis, Konstantinos Tserpes, and Spiros Pantelakis. "Computation of elastic moduli of nanocrystalline materials using Voronoi models of representative volume elements." MATEC Web of Conferences 188 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201818802006.

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In the present work, a numerical model is developed to predict the Young’s modulus and shear modulus of nanocrystalline materials using a Finite Element Analysis. The model is based on Representative Volume Elements (RVE) in which the microstructure of the material is described using the Voronoi tessellation algorithm. The use of the Voronoi particles was based on the observation of the morphology of nanocrystalline materials by Scanning Electron and Transmission Electron Microscopy. In each RVE, three-dimensional modelling of the grain and grain boundaries as randomly-shaped sub-volumes is performed. The developed model has been applied to pure nanocrystallline copper at grain volume fractions of 80%, 90% and 95% taking also into account the parameters of grain size and grain boundary thickness. The elastic moduli of nanocrystalline copper have been computed by loading the RVE in tension. The numerical results reveal that the elastic moduli of nanocrystalline copper increase with increasing the grain volume fraction. On the other hand, for a given grain volume fraction, the results showed no effect of the grain size. The model predictions have been validated successfully against numerical results from the literature and predictions of the Rule of Mixtures and the Mori-Tanaka analytical model.

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Sabochick, M. J., and J. A. Lupo. "Diffusion in Nanocrystalline Copper." Defect and Diffusion Forum 66-69 (January 1991): 555–60. http://dx.doi.org/10.4028/www.scientific.net/ddf.66-69.555.

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Heim, U., and G. Schwitzgebel. "Electrochemistry of nanocrystalline copper." Nanostructured Materials 12, no. 1-4 (January 1999): 19–22. http://dx.doi.org/10.1016/s0965-9773(99)00058-6.

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Witney, A. B., P. G. Sanders, J. R. Weertman, and J. A. Eastman. "Fatigue of nanocrystalline copper." Scripta Metallurgica et Materialia 33, no. 12 (December 1995): 2025–30. http://dx.doi.org/10.1016/0956-716x(95)00441-w.

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Zhou, Kai, and Ting Zhang. "Positron Lifetime Calculation for Plastic Deformed Nanocrystalline Copper." Defect and Diffusion Forum 373 (March 2017): 31–34. http://dx.doi.org/10.4028/www.scientific.net/ddf.373.31.

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Positron lifetime calculation has been performed on a computer-generated nanocrystalline copper with a mean grain size of 9.1 nm during its deformation. For the undeformed and deformed nanocrystalline copper, calculated positron lifetimes are around 157 ps which come from the positron annihilation in the free volume in grain boundaries. Due to the grain-boundary deformation mechanism, no vacancies or vacancy clusters will be induced in grains during the plastic deformation of the nanocrystalline copper, which is different to the deformation of the conventional polycrystal. From this point of view, in-situ positron annihilation measurements can provide important experimental information on the deformation mechanism of nanocrystalline metals.

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CAO, PENG, and DELIANG ZHANG. "THERMAL STABILITY OF NANOCRYSTALLINE COPPER FILMS." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 3830–35. http://dx.doi.org/10.1142/s0217979206040441.

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The grain growth kinetics of nanocrystalline copper thin film samples was investigated. The grain size of nanocrystalline copper samples was determined from the broadening of X-ray spectra. It was found that the grain size increased linearly with isothermal annealing time within the first 10 minutes, beyond which power-law growth kinetics is applied. The activation energy for grain growth was determined by constructing an Arrhenius plot, which shows an activation energy of about 21 – 30 kJ/mol. The low activation energy is attributed to the second phase particle drag and the porosity drag, which act as the pinning force for grain growth in nanocrystalline copper.

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Tanimoto, Hisanori, Nobuyori Yagi, Takanori Yamada, and Hiroshi Mizubayashi. "OS06W0399 Characterization and mechanical properties of high-density nanocrystalline copper." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2003.2 (2003): _OS06W0399. http://dx.doi.org/10.1299/jsmeatem.2003.2._os06w0399.

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Chen, Jin Song, Yin Hui Huang, Bin Qiao, Jian Ming Yang, and Yi Qiang He. "Rapid Prototyped Nanocrystalline Copper Parts by Jet Electrodeposition." Materials Science Forum 682 (March 2011): 3–7. http://dx.doi.org/10.4028/www.scientific.net/msf.682.3.

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The system components and the theory of jet electrodeposition orientated by rapid prototyping (RP) are introduced.The nanocrystalline copper parts with simple shape were fabricated by RP technology. The microstructure evolution of the nanocrystalline Copper layer was examined by means of the Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The results show that the jet electrodeposition can greatly enhance the limited current density, fine crystalline particles and improve deposition quality. The copper deposited layers have nanocrystalline microstructure with average size of 55.6nm. The grain size decreases to 41.4 nm in crystal plane (311).

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Saremi, M., and M. Abouie. "Oxidation and Corrosion Resistance of Nanocrystalline Copper Deposit Produced by Pulse Electrodeposition." Advanced Materials Research 264-265 (June 2011): 1519–25. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1519.

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Pulse electrodeposition was used to produce nanocrystalline (nc) copper from copper sulfate electrolyte with saccharin as additive. The grain size of nanocrystalline coatings was determined using x-ray diffraction and atomic force microscopy (AFM) which was about 30 nm. Microcrystalline copper deposits were also produced by direct current electrodeposition processes and compared with pulse plated ones. Corrosion behavior of the coatings was investigated using polarization and Impedance measurements in different solutions. The oxidation test was carried out at 650°C in an electrical furnace. It was demonstrated that the nanocrystalline film was markedly superior to regularly grained films made by direct current (DC) plating; nanocrystalline deposits show higher corrosion resistance and much higher oxidation resistance.

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Bazios, Panagiotis, Konstantinos Tserpes, and Spiros Pantelakis. "Prediction of mechanical properties of nanocrystalline materials using Voronoi FE models of representative volume elements." MATEC Web of Conferences 233 (2018): 00029. http://dx.doi.org/10.1051/matecconf/201823300029.

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In the present work, a numerical model is developed to predict the mechanical properties of nanocrystalline materials using a Finite Element Analysis. The model is based on Representative Volume Elements (RVE) in which the microstructure of the material is described using the Voronoi tessellation algorithm. The use of the Voronoi particles was based on the observation of the morphology of nanocrystalline materials by Scanning Electron and Transmission Electron Microscopy. In each RVE, three-dimensional modelling of the grain and grain boundaries as randomlyshaped sub-volumes is performed. The developed model has been applied to pure nanocrystallline copper taking into account the parameters of grain size and grain boundary thickness. The mechanical properties of nanocrystalline copper have been computed by loading the RVE in tension. The numerical results gave a clear evidence of grain size effect and the Hall-Petch relationship, which is a consequence of macroscopic strain being preferentially accumulated at grain boundaries. On the other hand, for a given grain volume fraction, the results for elastic moduli showed no effect of the grain size. The model predictions have been validated successfully against numerical results from the literature and predictions of the Rule of Mixtures and the Mori-Tanaka analytical model.

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Дисертації з теми "Nanocrystalline copper"

Deng, Hua. "Electrochemical Deposition of Nanocrystalline Copper and Copper-Based Composite Films." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-20020103-173702.

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Free-standing nanocrystalline copper-based composite and particle-free copper films were produced by direct- and pulse-current plating. Nanosize 50-nm Al2O3 or 5-nm diamond particles were codeposited into a copper matrix prepared on a rotating disk electrode (RDE). The electrolytes contained CuSO4.5H2O (0.25 M), H2SO4 (0.56 M or 1.5 M), 50-nm Al2O3 (12.5 g/L or 1.0 g/L) or 5-nm diamond (0.5 g/L) particles, and gelatine (0.1 g/L, 0.05 g/L, or 0.02 g/L). The deposition was carried out at room temperature. The RDE was rotated at 1800 rpm for high-alumina particle baths (12.5 g/L) and 1000 rpm for low-alumina particle (1.0 g/L), diamond particle (0.5 g/L), and particle-free baths. The free-standing composite and copper films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), micro hardness tester, and transmission electron microscopy (TEM). Grain size and crystal texture were obtained by XRD measurement. SEM gave information on surface morphology and composition of films. The hardness of nanocrystalline materials was measured by micro hardness tester. TEM was used to confirm the presence of nanocrystalline copper grains. The uncompensated potential became more cathodic with increasing current density in pulse-current plating. The current efficiency was in the range of 0.93 ¨C 1.09 for both direct- and pulse-current plating. Gelatine concentration, the presence of nanosize dispersoids, and pH have no significant effect on electrode potential and current efficiency. Grain size decreased with increasing current density for particle-free copper and most of the composite films by direct- and pulse-current plating. The microhardness of nanocrystalline materials was increased by decreasing grain size for most of the particle-free copper and composite films. The existence of high-angle grain boundaries in nanocrystalline films resulted in negative Hall-Petch slopes. The presence of low concentration of alumina or diamond particles had no effect on grain size and microhardness. The pH had no obvious influence on grain size, microhardness, and alumina content in composite films. Random crystal texture is observed for Cu-Al2O3 composite and particle-free copper films and the (111) preferred texture for Cu-diamond composite films. The (100) preferred substrate orientation had no effect on deposit texture. The current density for both direct- and pulse-current plating had no significant effect on material texture. The presence of particles has no significant influence on nanocrystalline texture. Surface morphology varied for films made under different bath conditions. High gelatine concentration resulted in low-particle impregnation. Films made using 0.1 g/L gelatine resulted in spherical particles with grain size of 64 nm and porous surface. Films made using 0.02 g/L gelatine resulted in smooth surface with smaller grains of 40 nm. Films with high-alumina particle embedding, for example sample 7/9-1, resulted in porous and dark surface. High-alumina particle concentration (12.5 g/L) with 0.02 g/L gelatine in the deposition baths resulted in high-alumina content (0.11 wt% - 2.76 wt%) in composite films. The higher current density (297 mA/cm2) resulted in the lower alumina particle (0.076 wt%) embedding rate for the same bath parameter setting. The presence of both Al and O was found in copper-alumina composites and C element (diamond) was detected in copper-diamond composite films by EDS.

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Haouaoui, Mohammed. "An investigation of bulk nanocrystalline copper fabricated via severe plastic deformation and nanoparticle consolidation." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4861.

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Ultrafine grained (UFG) and nanocrystalline materials have attracted considerable interest because of their unique mechanical properties as compared with coarse grained conventional materials. The fabrication of relatively large amounts of these materials still remains a challenge, and a thorough understanding of the relationship between microstructure and mechanical properties is lacking. The objective of this study was to investigate the mechanical properties of UFG and nanocrystalline copper obtained respectively by a top down approach of severe plastic deformation of wrought copper and a bottom up approach of consolidation of copper nanoparticles using equal channel angular extrusion (ECAE). A critical assessment and correlation of the mechanical behavior of ECAE processed materials to the microstructure was established through the determination of the effect of strain level and strain path on the evolution of strength, ductility and yield anisotropy in UFG oxygen free high conductivity copper in correlation with grain size, grain morphology and texture. ECAE was shown to be a viable method to fabricate relatively large nanocrystalline consolidates with excellent mechanical properties. Tensile strengths as high as 790 MPa and fracture strain of 7 % were achieved for consolidated 130nm copper powder. The effects of extrusion route, number of passes and extrusion rate on consolidation performance were evaluated. The relatively large strain observed was attributed to the bimodal grain size distribution and accommodation by large grains. The formation of bimodal grain size distribution also explains the simultaneous increase in strength and ductility of ECAE processed wrought Cu with number of passes. Texture alone cannot explain the mechanical anisotropy in UFG wrought copper but we showed that grain morphology has a strong impact and competes with texture and grain refinement in controlling the resulting yield strength. Tension-compression asymmetry was observed in UFG wrought copper. This asymmetry is not always in favor of compression as reported in literature, and is also influenced by grain morphology through the interaction of dislocations with grain boundaries. Different prestrains in tension and compression should be experimented to have a better understanding of the encountered anisotropy in Bauschinger parameter in relation with the observed tension-compression asymmetry.

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Gandy, David R. "Shear deformation of amorphous and nanocrystalline copper microstructures via atomistic simulation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40424.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (p. 24).
In the well-known Hall-Petch behavior, yield and flow stresses in polycrystalline metals increase with a decrease in grain size. As grain size continues to decrease, mechanical strength peaks. As grain size further decreases, mechanical strength begins to decrease. As grain size approaches zero, the total structure is composed of an increasingly high percentage of grain boundaries, which exhibit the properties of an amorphous structure. Molecular dynamics simulations, with the goal of exploring this behavior, were performed on nanocrystalline and amorphous microstructures using the embedded atom potential developed by Mishin et al. A 0.2 shear strain was applied to each of the nanocrystalline and amorphous samples. From these simulations, we have observed the inverse Hall-Petch behavior of nanocrystalline structures. We have also shown that the amorphous structure as zero grain size is reasonable as the limiting case for the inverse Hall-Petch trends in nanocrystalline structures.
by David R. Gandy.
S.B.

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Xu, Tao. "The structure-property relation in nanocrystalline materials: a computational study on nanocrystalline copper by Monte Carlo and molecular dynamics simulations." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37108.

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Nanocrystalline materials have been under extensive study in the past two decades. The reduction in grain size induces many abnormal behaviors in the properties of nanocrystalline materials, that have been investigated systematically and quantitatively. As one of the most fundamental relations in materials science, the structure-property relation should still apply on materials of nano-scale grain sizes. The characterization of grain boundaries (GBs) and related entities remains a big obstacle to understanding the structure-property relation in nanocrystalline materials. It is challenging experimentally to determine the topological properties of polycrystalline materials due to the complex and disordered grain boundary network presented in the nanocrystalline materials. The constantly improving computing power enables us to study the structure-property relation in nanocrystalline materials via Monte Carlo and molecular dynamic simulations. In this study, we will first propose a geometrical construction method based on inverse Monte Carlo simulation to generate digital microstructures with desired topological properties such as grain size, interface area, triple junction length as well as their statistical distributions. The influences on the grain shapes by different topological properties are studied. Two empirical geometrical laws are examined including the Lewis rule and Aboav-Weaire law. Secondly, defect free nanocrystalline Copper (nc-Cu) samples are generated by filling atoms into the Voronoi structure and then relaxed by molecular dynamics simulations. Atoms in the relaxed nc-Cu samples are then characterized into grain atoms, GB interface atoms, GB triple junction atoms and vertex atoms using a newly proposed method. Atoms in each GB entity can also be identified. Next, the topological properties of nc-Cu samples before and after relaxation are calculated and compared, indicating that there exists a physical limit in the number of atoms to form a stable grain boundary interface and triple junction in nanocrystalline materials. In addition, we are able to obtain the statistical averages of geometrical and thermal properties of atoms across each GB interfaces, the so-called GB profiles, and study the grain size, misorientation and temperature effects on the microstructures in nanocrystalline materials. Finally, nc-Cu samples with different topological properties are deformed under simple shear using MD simulation in an attempt to study the structure-property relation in nanocrystalline materials.

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Marple, William J. "The cold gas-dynamic spray and characterization of microcrystalline and nanocrystalline copper alloys." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27864.

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Outstanding Thesis
Approved for public release; distribution is unlimited
This thesis presents research on the cold gas-dynamic spray processa relatively new technology that may be utilized to create metal coatings in the solid state. While the thermodynamics and fluid mechanics of the cold gas-dynamic spray process are well understood, the effects of feedstock powder microstructure and composition on the deposition process remain largely unknown. In particular, this thesis aims to shed light on these effects as they pertain to common face-centered cubic metals and their alloysnotably copper and brass. Deposition efficiency, coating thickness per pass, hardness, porosity and compositional variance were all characterized as functions of spraying pressure, spraying temperature and feedstock particle composition in each of the materials. This thesis presents evidence that while brass can be deposited using cold gas-dynamic spray, the resulting material does not possess a dense, uniform microstructure. In fact, deposits made with Cu-90/10 wt.% Zn brass have more than 400% more porosity than standard copper coatings, possess extensive microstructural cracking and wide compositional variance from grain to grain.

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Cretu, V., V. Postica, N. Ababii, F. Schütt, M. Hoppe, D. Smazna, V. Trofim, V. Sontea, R. Adelung, and O. Lupan. "Ethanol Sensing Performances of Zinc-doped Copper Oxide Nano-crystallite Layers." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42506.

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The synthesis via chemical solutions (aqueous) (SCS) wet route is a low-temperature and cost-effective growth technique of high crystalline quality oxide semiconductors films. Here we report on morphology, chemical composition, structure and ethanol sensing performances of a device prototype based on zincdoped copper oxide nanocrystallite layer. By thermal annealing in electrical furnace for 30 min at temperatures higher than 550 ˚C, as-deposited zinc doped Cu2O samples are converted to tenorite, ZnxCu1-xOy, (x=1.3wt%) that demonstrate higher ethanol response than sensor structures based on samples treated at 450 ˚C. In case of the specimens after post-growth treatment at 650 ˚C was found an ethanol gas response of about 79 % and 91 % to concentrations of 100 ppm and 500 ppm, respectively, at operating temperature of 400 ˚C in air.

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Traiviratana, Sirirat. "A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3337304.

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Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed Jan. 9, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 179-188).

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Bansal, Shubhra. "Characterization of Nanostructured Metals and Metal Nanowires for Ultra-High Density Chip-to-Package Interconnections." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14041.

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Nanocrystalline materials are being explored as potential off-chip interconnects materials for next generation microelectronics packaging. Mechanical behavior and deformation mechanisms in nanocrystalline copper and nickel have been explored. Nanostructured copper interconnections exhibit better fatigue life as compared to microcrystalline copper interconnects at a pitch of 100 and #956;m and lower. Nanocrystalline copper is quite stable upto 100 oC whereas nickel is stable even up to 400 oC. Grain boundary (GB) diffusion along with grain rotation and coalescence has been identified as the grain growth mechanism. Ultimate tensile and yield strength of nanocrystalline (nc) Cu and Ni are atleast 5 times higher than microcrystalline counterparts. Considerable amount of plastic deformation has been observed and the fracture is ductile in nature. Fracture surfaces show dimples much larger than grain size and stretching between dimples indicates localized plastic deformation. Activation energies for creep are close to GB diffusion activation energies indicating GB diffusion creep. Creep rupture at 45o to the loading axis and fracture surface shows lot of voiding and ductile kind of fracture. Grain rotation and coalescence along direction of maximum resolved shear stress plays an important role during creep. Grain refinement enhances the endurance limit and hence high cycle fatigue life. However, a deteriorating effect of grain refinement has been observed on low cycle fatigue life. This is because of the ease of crack initiation in nanomaterials. Persistent slip bands (PSBs) at an angle of 45o to loading axis are observed at higher strain ranges (> 1% for nc- Cu) with a width of about 50 nm. No relationship has been observed between PSBs and crack initiation. A non-recrystallization annealing treatment, 100 oC/ 2 hrs for nc- Cu and 250 oC/ 2 hrs for nc- Ni has been shown to improve the LCF life without lowering the strength much. Fatigue crack growth resistance is higher in nc- Cu and Ni compared to their microcrystalline counterparts. This is due to crack deflection at GBs leading to a tortuous crack path. Nanomaterials exhibit higher threshold stress intensity factors and effective threshold stress intensity is proportional to the elastic modulus of the material.

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Ke, Xing. "Atomistic Simulation Studies Of Grain-Boundary Segregation And Strengthening Mechanisms In Nanocrystalline Nanotwinned Silver-Copper Alloys." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/995.

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Silver (Ag) is a precious metal with a low stacking fault energy that is known to form copious nanoscale coherent twin boundaries during magnetron sputtering synthesis. Nanotwinned Ag metals are potentially attractive for creating new interface-dominated nanomaterials with unprecedented mechanical and physical properties. Grain-boundary segregation of solute elements has been found to increase the stability of interfaces and hardness of nanocrystalline metals. However, heavily alloying inevitably complicates the underlying deformation mechanisms due to the hardening effects of solutes, or a change of stacking fault energies in Ag caused by alloying. For the above reasons, we developed a microalloying (or doping) strategy by carefully selecting Cu as the primary impurity – a solute that is predicted to have no solid-solution strengthening effect in Ag when its content is below 3.0 wt.%. Neither will Cu affect the stacking fault energy of Ag at a concentration <1.0 wt.%. Moreover, Cu atoms are ~12% smaller than Ag ones, and Ag-Cu is an immiscible system, which facilitates the segregation of Cu into high-energy interface sites such as grain-boundaries and twin-boundary defects. In this thesis, large-scale hybrid Monte-Carlo and molecular dynamics simulations are used to study the unexplored mechanical behavior of Cu-segregated nanocrystalline nanotwinned Ag. First, the small-scale mechanics of solute Cu segregation and its effects on incipient plasticity mechanisms in nanotwinned Ag were studied. It was found that solute Cu atoms are segregated concurrently to grain boundaries and intrinsic twin-boundary kink-step defects. Low segregated Cu contents (< 1 at.%) are found to substantially increase twin-defect stability, leading to a pronounced rise in yield strength at 300 K. Second, atomistic simulations with a constant grain size of 45 nm and a wide range of twin boundary spacings were performed to investigate the Hall-Petch strength limit in nanocrystalline nanotwinned Ag containing either perfect or kinked twin boundaries. Three distinct strength regions were discovered as twin boundary decreases, delineated by normal Hall-Petch strengthening with a positive slope, the grain-boundary-dictated mechanism with near-zero Hall-Petch slope, and twin-boundary defect induced softening mechanism with a negative Hall-Petch slope. Third, by systematically studying smaller grain sizes, we find that the “strongest” size for pure nanotwinned Ag is achieved for a grain size of ~16 nm, below which softening occurs. The controlling plastic deformation mechanism changes from dislocation nucleation to grain boundary motion. This transition decreases to smaller grain sizes when Cu contents are segregated to the interfaces. Our simulations show that continuous Hall-Petch strengthening without softening, down to grain sizes as small as 6 nm, is reached when adding Cu atoms up to 12 at. %. For Cu contents ≥ 15 at. %, however, the predominant plastic deformation mechanism changes to shear-band induced softening. The present thesis provides new fundamental insights into solute segregation, and strengthening mechanisms mediated by grain boundaries and twin boundaries in face-centered cubic Ag metals, which is expected to motivate experimental studies on new nanotwinned metals with superior mechanical properties controlled by microalloying.

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Tiwari, Shreevant. "Methods for atomistic input into the initial yield and plastic flow criteria for nanocrystalline materials." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53059.

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Nanocrystalline (NC) metals and alloys are known to possess superior mechanical properties, e.g., strength, hardness, and wear-resistance, as compared to conventional microcrystalline materials. NC metals are characterized by a mean grain size <100 nm; in this grain size regime, inelastic deformation can occur via a combination of interface-mediated mechanisms viz., grain boundary sliding/migration, and dislocation nucleation from grain boundary sources. Recent studies have suggested that these interface-mediated inelastic deformation mechanisms in fcc metals are influenced by non-glide stresses and interfacial free volume, unlike dislocation glide mechanisms that operate in microcrystalline fcc metals. Further, observations of tension-compression strength asymmetry in NC metals raise the possibility that yield and inelastic flow in these materials may not be adequately described by solely the deviatoric stress. Unfortunately, most literature concerning the mechanical testing of NC metals is limited to uniaxial deformation or nanoindentation techniques, and the multiaxial deformation behavior is often predicted assuming initially isotropic yield and subsequent flow normal to the yield surface. The primary objective of this thesis is to obtain a better understanding of the nature of inelasticity in NC metals by simulating multiaxial deformation at the atomistic resolution, and developing methods to interpret the results in ways that would be useful from a continuum constitutive modeling viewpoint. First, we have presented a novel, statistical mechanics-based approach to unambiguously resolve the elastic-plastic transition as an avalanche in the proliferation of mobile defects. This approach is applied to nanocrystalline Cu to explore the influence of pressure and multiaxial stress states on the inelastic deformation behavior. The results suggest that initial yield in nanocrystalline Cu under biaxial loading is only weakly anisotropic in the 5 nm grain size regime, and that plastic flow evolves in a direction normal to the von Mises yield surface. However, triaxial deformation simulations reveal a significant effect of the superimposed hydrostatic stress on yielding under shear. These results are analyzed in detail in order to assess the influence of pre-existing internal stresses and interfacial excess volume on the inelastic deformation behavior. Further, we have studied the effects of imposed hydrostatic pressure on the shear deformation behavior of Cu bicrystals containing symmetric tilt interfaces, as well as Cu nanocrystals of different grain sizes. Most interfaces exhibit an increase in shear strength with imposed compressive hydrostatic pressure. However, for some interfaces, this trend is reversed. Neither the sign nor the magnitude of the pressure-induced elevation in shear strength appears to correlate with interface structure or particular deformation mechanism(s). In Cu nanocrystals, we observe that imposed compressive pressure leads to strengthening under shear deformation, and the effect of imposed pressure on the shear strength becomes stronger with increase in grain size or temperature. Activation parameters for shear deformation have been computed for these nanocrystals, and computed values seem to agree with existing experimental and theoretical estimates. Finally, we have proposed some modifications to conventional isothermal molecular dynamics algorithms, in order to isolate dislocation nucleation events from interfacial sources, and thereby permit explicit computation of the activation parameters for such events.

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Частини книг з теми "Nanocrystalline copper"

Kommel, Lembit, Jakob Kybarsepp, Renno Veinthal, and Rainer Traksmaa. "Fabrication, Control and Properties of Nanocrystalline Copper." In Nano-Architectured and Nanostructured Materials, 27–37. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606017.ch5.

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Sircar, Avirup, and Puneet Kumar Patra. "Mechanical Properties of Nanocrystalline Copper/CNT Nanocomposites." In Lecture Notes in Mechanical Engineering, 337–47. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-6490-8_28.

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Rigsbee, J. M. "Development of Nanocrystalline Copper-Refractory Metal Alloys." In Materials Science Forum, 2373–78. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-462-6.2373.

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Baláz, Peter, E. Boldižárová, and E. Godočíková. "Preparation of Nanocrystalline Copper and Copper Silicon Sulphide by Mechanochemical Route." In Materials Science Forum, 453–56. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-962-8.453.

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Guo, Lu, Wang Shuaichuang, and Zhang Guangcai. "Molecular Dynamics Simulation on Plastic Deformation of Nanocrystalline Copper." In Dynamic Behavior of Materials, Volume 1, 203–13. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4238-7_27.

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Sreedhar, A., M. Hari Prasad Reddy, and S. Uthanna. "Substrate Bias Influenced Physical Characteristics of Nanocrystalline Silver Copper Oxide Films." In Springer Proceedings in Physics, 465–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-34216-5_46.

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Gordo, P. M., M. F. Ferreira Marques, and M. T. Vieira. "Positron Annihilation Study on Nanocrystalline Copper Thin Films Doped with Nitrogen." In Advanced Structured Materials, 15–24. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-50784-2_2.

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Chen, Kaiguo, S. Q. Shi, and J. Lu. "Deformation Twin Induced by Multi-strain in Nanocrystalline Copper: Molecular Dynamic Simulation." In Proceedings of the 1st World Congress on Integrated Computational Materials Engineering (ICME), 171–76. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118147726.ch23.

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Wang, Yu-Ting, Yun-Fu Shieh, Chien-hua Chen, Cheng-hua Lu, Ya-Chi Cheng, Chung-Lin Wu, and Ming-Tzer Lin. "In Situ Energy Loss and Internal Friction Measurement of Nanocrystalline Copper Thin Films Under Different Temperature." In MEMS and Nanotechnology, Volume 8, 67–73. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07004-9_8.

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Chiang, M. J., C. W. Wu, and H. E. Cheng. "Effect of Oxygen Flow Rate and Temperature on the Structure of DC Sputtered Nanocrystalline Copper Oxide Films." In Semiconductor Photonics: Nano-Structured Materials and Devices, 129–31. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-471-5.129.

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Тези доповідей конференцій з теми "Nanocrystalline copper"

Lang, Eric, E. Homer, J. Bair, Michael Marshall, Henry Padilla, Brad Boyce, D. Frazer, P. Hosemann, and Khalid Hattar. "In-situ TEM Cryoindentation of Nanocrystalline Copper ." In Proposed for presentation at the Microscopy and Microanalysis 2021 in ,. US DOE, 2021. http://dx.doi.org/10.2172/1888433.

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Das, Rashmita, Basanta K. Das, Rohit Shukla, T. Prabaharan, and Anurag Shyam. "Production of nanocrystalline copper by exploding wire method." In SOLID STATE PHYSICS: Proceedings of the 56th DAE Solid State Physics Symposium 2011. AIP, 2012. http://dx.doi.org/10.1063/1.4709956.

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Wu, C. W., J. R. Wu, and M. J. Chiang. "Deposition of nanocrystalline copper oxide films for solar cell application." In 2007 IEEE Conference on Electron Devices and Solid-State Circuits. IEEE, 2007. http://dx.doi.org/10.1109/edssc.2007.4450215.

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Das, Rashmita, Basanta Kumar Das, and Anurag Shyam. "Particle distribution of nanocrystalline copper produced by exploding wire method." In SOLID STATE PHYSICS: PROCEEDINGS OF THE 57TH DAE SOLID STATE PHYSICS SYMPOSIUM 2012. AIP, 2013. http://dx.doi.org/10.1063/1.4790968.

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Chiu, Wei-Lan, Ou-Hsiang Lee, Chia-Wen Chiang, and Hsiang-Hung Chang. "Low-Temperature Wafer-to-Wafer Hybrid Bonding by Nanocrystalline Copper." In 2022 IEEE 72nd Electronic Components and Technology Conference (ECTC). IEEE, 2022. http://dx.doi.org/10.1109/ectc51906.2022.00114.

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Yanilkin, Alexey V., Alexey Yu Kuksin, Genri E. Norman, Vladimir V. Stegailov, Mark Elert, Michael D. Furnish, Ricky Chau, Neil Holmes, and Jeffrey Nguyen. "ATOMISTIC SIMULATIONS OF FRACTURE IN NANOCRYSTALLINE COPPER UNDER HIGH STRAIN RATES." In SHOCK COMPRESSION OF CONDENSED MATTER - 2007: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. AIP, 2008. http://dx.doi.org/10.1063/1.2833052.

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Jung Joon Yoo, Jae Yong Song, Jin Yu, Ho Ki Lyeo, Sungjun Lee, and Jun Hee Hahn. "Multi-walled carbon nanotube/nanocrystalline copper nanocomposite film as an interconnect material." In 2008 58th Electronic Components and Technology Conference (ECTC 2008). IEEE, 2008. http://dx.doi.org/10.1109/ectc.2008.4550140.

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Daryadel, Soheil, Ali Behroozfar, S. Reza Morsali, Rodrigo A. Bernal, and Majid Minary. "Additive Manufacturing of Metals at Micro/Nanoscale by Localized Pulsed Electrodeposition: Nanotwinned Copper Nanowires." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6552.

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Анотація:

Direct printing of three-dimensional nanoscale metallic wires with controlled microstructure is useful for applications in the 3D integrated circuits, flexible electronics and nanoelectronics. In this paper, we demonstrate the localized pulsed electrodeposition process for direct printing of 3D free-standing nanotwinned Copper (nt-Cu) nanowires. Nt-Cu offers unique mechanical and electrical properties, which are advantageous in different applications. Focused ion beam (FIB) analysis confirmed the nanocrystalline nanotwinned (nc-nt) microstructure of the wires. Mechanical properties of the 3D printed nc-nt Cu were characterized using in situ SEM micro-compression experiments. The 3D printed nc-nt Cu exhibited a flow stress of over 960 MPa, which is outstanding for an additively manufactured material.

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Handrigan, Stephen, and Sam Nakhla. "Influence Of Forcefield Selection On The Formation Of Viable Nanocrystalline Copper Structures Using The Melt Cool Method." In Canadian Society for Mechanical Engineering International Congress (2021 : Charlottetown, PE). Charlottetown, P.E.I.: University of Prince Edward Island. Robertson Library, 2021. http://dx.doi.org/10.32393/csme.2021.123.

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Chen, Jin-Song, Yin-Hui Huang, Zhi-Dong Liu, and Zong-Jun Tian. "Jet Electrodeposited Cu-Al2O3 Nanocomposite Coatings." In 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21103.

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Анотація:

A jet electrodeposition device was carried out to prepare Cu-Al2O3 nanocomposite coatings. The influence of the concentration of Al2O3 in the electrolyte and parameters, such as cathodic current density, the electrolyte temperature as well as the electrolyte jet velocity, on the content of the Al2O3 in the deposite were investigated. The coatings ingredient and microstructure was measured by the scanning electron microscope (SEM) with energy dispersive analyzer system (EDX), the microhardness tests were conducted on an microhardness tester. The results show that the jet electrodeposition can fine crystalline particles. The copper deposited layers have nanocrystalline microstructure with grain size of about 50nm. The amount of Al2O3 in composites first increased and then decreased with an increase in the concentration of Al2O3, current density, temperature and jet velocity. The composite with optimum atomic percent of Al2O3 (14.4 at%) can be obtained at the concentration of 30 g/l, cathodic current densities 300 A/dm2, temperature 30°C, and electrolyte jet velocity 8 m/s. The addition of Al2O3 in copper increases the microhardness of the electrodeposited coatings.

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Звіти організацій з теми "Nanocrystalline copper"

Sanders, P. G., J. R. Weertman, and J. A. Eastman. Tensile behavior of nanocrystalline copper. Office of Scientific and Technical Information (OSTI), November 1995. http://dx.doi.org/10.2172/201763.

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Hall, Aaron Christopher, Pylin Sarobol, Nicolas Argibay, Blythe Clark, and Christopher Diantonio. Solid state consolidation nanocrystalline copper-tungsten using cold spray. Office of Scientific and Technical Information (OSTI), September 2015. http://dx.doi.org/10.2172/1222928.

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