bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Frequency Field Effects on Ionic Defect Concentrations and Solid-State Diffusion Processes
Authors: Freeman S. A. , Booske J. H. , Cooper R. F. 
Published: April 2011

AbstractWe describe computer simulations of a microwave-induced driving force for ionic transport. The simulations are based on a model which predicts rectification of ionic fluxes at interfaces and a resulting depletion or accumulation of defects near the interface. Some details of the model are discussed, results of the simulations are presented, and the impact of these effects on sintering and diffusion is discussed.
Modifications on Bulk Crystallization of Glasses Belonging to M2O-CaO-SiO2-ZrO2 System in A 2.45 GHz Microwave Field
Authors: Siligardi C. , Leonelli C. , Fang Y. , Agrawal D. 
Published: April 2011

AbstractThe potential for microwave processing of a single phase material is often limited due to the dependence of dielectric losses upon the chemical bonding and temperature of the material. We will present results showing the effect of microwave absorption on bulk crystallization of glasses belonging to M2O-CaO-SiO2-ZrO2 system (where M+ Li, Na, K). The glass samples were devitrified using both microwave and conventional heating. The effect of Li+, Na+, K+ on crystallization is quite remarkable and is a function of ion size. This is true especially in the microwave heating where the important dielectric losses observed in silicate glasses are related to the motion of alkali cations throughout the glass matrix. X-ray diffraction analysis was performed on the powdered samples to determine crystalline phases. Results of microstructure and microanalysis on these glass-ceramic samples will also be presented.
Adhesive Bonding Via Exposure to Variable Frequency Microwave Radiation
Authors: Paulauskas Felix L. , McMillan April D. , Warren C. David 
Published: April 2011

AbstractAdhesive bonding through the application of variable frequency microwave (VFM) radiation has been evaluated as an alternative curing method for joining composite materials. The studies showed that the required cure time of a thermosetting epoxy adhesive is substantially reduced by the use of VFM when compared to conventional (thermal) curing methods. Variable frequency microwave processing appeared to yield a slight reduction in the required adhesive cure time when compared to processing by the application of single frequency microwave radiation. In contrast to the single frequency processing, the variable frequency methodology does not readily produce localized overheating (burnt or brown spots) in the adhesive or the composite. This makes handling and location of the sample in the microwave oven less critical for producing high quality bonds and allows for a more homogeneous distribution of the cure energy. Variable frequency microwave processing is a valuable alternative method for rapidly curing thermoset adhesives at low input power levels.
Microwave Treatment of Emissions From Waste Materials
Authors: Schulz R. L. , Folz D. C. , Clark D. E. , Schmidt C. J. , Wicks G. G. 
Published: April 2011

AbstractA microwave off-gas system has been designed and fabricated to destroy or decompose emissions that arise from microwave treatment of printed circuit boards (PCBs). Preliminary gas chromatography data on emissions that resulted from combustion of PCBs showed significant decreases in the concentration and number of hazardous compounds detected in the off-gases after treatment. Investigations have continued in this area to demonstrate the reproducibility of the initial results and to determine critical control parameters for optimization of the system. The results of these studies are presented.
Monitoring Resin Cure Of Medium Density Fiberboard Using Dielectric Sensors
Authors: King R. J. , Rice R. W. 
Published: April 2011

AbstractFlush mounted, in-press microwave (600–800 MHz) sensors have been developed for monitoring the complex permittivity in real time during the cure of medium density fiberboard. The measured dielectric constant (ε')a nd loss factor (ε") are independent diagnostic indicators of dynamic cure events that are catalyzed by heat, pressure and moisture. In particular, with this technique the instantaneous effects of resin viscosity, rate and degree of adhesive cure, the wood density, the changes in phase of the moisture and the rate of moisture depletion can be monitored during the entire curing process.The comparative roles of moisture and adhesive content are discussed, along with the comparative modulus of rupture with cure duration. Results are presented comparing the dynamics of phenol-formaldehyde and isocyanate resins.
Mapping the ε” of Conducting Solid Films in Situ
Authors: Werner M. J. , King R. J. 
Published: April 2011

AbstractTwo nondestructive microwave methods for sensing and mapping the local loss factor ε” of conducting solid films are described. Example results of both methods are compared to the low frequency sheet resistance as measured by two- and four-point probe methods. Specimens ranged from 26 to 10,000 ohms per square. Depending on the test frequency, spatial resolution of about 1 cm is achievable, as demonstrated by maps of ε”.
Transient Enhanced Diffusion of Boron in Silicon:The Interstitial Flux
Authors: Simpson T. W. , Goldberg R. D. , Mitchell I. V. , Baribeau J.-M. 
Published: April 2011

AbstractDelta-doped boron marker layers in silicon have been used to test further the relationship between B transient enhanced diffusion (TED) and the flux of silicon interstitials released during the annealing stage following self implantation. We present new data which address a number of questions raised by the present models. We show that in our experiments bulk trapping of interstitials is significant only for low implant fluences (˜1012 cm2). The origin of the observed diffusion-like profiles for the interstitial flux is instead found to lie in local trapping within the δ-doped layers themselves. Boron trapped in immobile clusters may be associated with Si interstitials in approximately a 1:1 ratio; nevertheless this trapping contribution alone may not entirely account for the observed gradient. We suggest that some part of the observed TED response with depth is attributable to local trapping of silicon interstitials within the boron doped layers.
Investigations of Plasma Immersion Ion Implantation Hydrogenation for Poly-Si Tfts Using an Inductively Coupled Plasma Source
Authors: Zhou Yuanzhong , Qin Shu , Chan Chung 
Published: April 2011

AbstractA plasma immersion ion implantation (Pill) hydrogenation process using an inductively-coupled plasma (ICP) source is implemented for defect passivation in polycrystalline silicon (poly-Si) thin film transistors (TFT's). Device parameter improvement saturates in 4 minutes, which is considerably shorter than for other reported hydrogenation methods. Stress test indicates that the devices hydrogenated by this novel technique have much better long-term reliability. The hydrogenation effects on two types of trap states are analyzed the current-voltage characteristics of the devices. The densities of deep states and tail states are significantly reduced after short time hydrogenation.
Cascade Defects Beyond the Primary Damage State
Authors: Heinisch H. L. 
Published: April 2011

AbstractAtomic scale computer simulations are used to investigate the intracascade evolution of the defect distributions of cascades in copper over macroscopic times. Starting with cascades generated using molecular dynamics, the diffusive transport and interactions of the defects are followed for hundreds of seconds in stochastic annealing simulations. The temperature and energy dependencies of annihilation, clustering and free defect production are determined for individual cascades. The simulation results illustrate the strong influence on intracascade evolution of the defect configuration existing in the primary damage state. Other significant factors affecting the evolution of the defect distribution are the large differences in mobility and stability of vacancy and interstitial defects and the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. The latter factor introduces a cascade energy dependence of defect evolution that is apparent only beyond the primary damage state, amplifying the need for performing many more cascade simulations at higher energies.
Defect Cluster Structure and Tensile Properties of Copper Single Crystals Irradiated With 600 MeV Protons
Authors: Dai Yong , Victoria Max 
Published: April 2011

AbstractThe defect microstructures and tensile properties of high purity copper single crystals have been studied after irradiation at room temperature with 600 MeV protons in the dose range from 10-3to 10-1dpa. The defect number density N of clusters shows a linear dependence with dose up to a saturation value of 4×1023m-3, with a broad transition region between doses of 3×10-3and 10-1dpa. The increase in critical resolved shear stress (CRSS) induced by the irradiation is proportional to the square root of the dose, up to a dose of 7×10-3dpa. These results are compared to those of both fission and fusion neutron irradiations, showing that in room temperature irradiations at low fluences, no recoil spectra effects can be detected.
Effects of Heavy-Ion Irradiation on Microstructure of V-4Cr-4Ti Alloy at Moderate Temperatures
Authors: Gazda J. , Chung H. M. , Loomis B. A. , Meshii M. 
Published: April 2011

AbstractV-4 wt.% Cr-4 wt.% Ti alloy is a promising candidate material for first-wall and structural applications in magnetic fusion reactors. In the past, fast neutron sources were used to evaluate postirradiation properties of fusion candidate materials. The recent shutdowns of the Fast Flux Test Facility (FFTF) and the Experimental Breeder Reactor (EBR-II) left U.S. researchers without local experimental facilities for such tests. Under such circumstances, ease of experimental control, availability, and relatively low cost make heavy-ion irradiation an attractive alternative, provided its limitations are appreciated. We selected 3-MeV V+ and 4.5-MeV Ni++ ions to investigate the effects of irradiation on the microstructure of V-4Cr-4Ti alloy in the temperature range of 200 – 420°C. The main interest is in the evaluation of this alloy's dimensional stability and susceptibility to irradiation embrittlement. In this paper, we report results of ion irradiation experiments and compare them with available data on fast-neutron irradiation. From transmission electron microscopy (TEM) analysis of ion-irradiated specimens, we found that the dominant feature of the postirradiation microstructure was a high density of dislocation loops and pointdefect clusters. Density and defect size depended on irradiation dose and temperature. Precipitates and voids/bubbles were not observed, even in specimens that were simultaneously injected with He and exposed to heavy-ion irradiation. Increased transport of point defects to internal interfaces was observed, as manifested by defect denuded zones along grain boundaries, Defect denuded zones along grain boundaries could lead to segregation of impurities and solutes and formation of precipitates on grain boundaries.
Defect Microstructures and Deformation Mechanisms in Irradiated Austenitic Stainless Steels
Authors: Bruemmer S. M. , Cole J. I. , Carter R. D. , Was G. S. 
Published: April 2011

AbstractMicrostructural evolution and deformation behavior of austenitic stainless steels are evaluated for neutron, heavy-ion and proton irradiated materials. Radiation hardening in austenitic stainless steels is shown to result from the evolution of small interstitial dislocation loops during lightwater-reactor (LWR) irradiation. Available data on stainless steels irradiated under LWR conditions have been analyzed and microstructural characteristics assessed for the critical fluence range (0.5 to 10 dpa) where irradiation-assisted stress corrosion cracking susceptibility is observed. Heavy-ion and proton irradiations are used to produce similar defect microstructures enabling the investigation of hardening and deformation mechanisms. Scanning electron, atomic force and transmission electron microscopies are employed to examine tensile test strain rate and temperature effects on deformation characteristics. Dislocation loop microstructures are found to promote inhomogeneous planar deformation within the matrix and regularly spaced steps at the surface during plastic deformation. Twinning is the dominant deformation mechanism at rapid strain rates and at low temperatures, while dislocation channeling is favored at slower strain rates and at higher temperatures. Both mechanisms produce highly localized deformation and large surface slip steps. Channeling, in particular, is capable of creating extensive dislocation pileups and high stresses at internal grain boundaries which may promote intergranular cracking.
Microstructure Evolution of Selected Ferriticmartensitic Steels under Dual-Beam Irradiation
Authors: Wanderka Nelja , Camus Eric , Wollenberger Heinrich 
Published: April 2011

AbstractWe present experimental results on the microstructure evolution of dual-beam irradiated (300 keV heavy ions plus 15 keV helium ions) ferritic-martensitic steels (Manet, DIN 1.4926, F82H mod). The helium bubble morphology as well as microchemistry of the alloys are investigated by means of transmission electron microscopy and field-ion microscopy with atom probe. The alloys were irradiated to fluences up to 50 dpa and implanted with helium up to a concentration of 1 at.% at the temperatures of 723 K and 773 K. The damage and implantation rates variied from 2.5 · 10−3 dpa/s to 2.5·10−2 dpals and from 0.5 appmls to 5 appm/s, respectively. Size and number density of helium bubbles is found to be rate dependent. Smaller implantation rates produce larger helium bubbles and smaller bubble number densities. Regions of local enrichment of alloy elements, typically 5 nm in size, containing chromium (up to 40 at.%), silicon, and nickel are detected. Number densities of helium bubbles and of regions of chromium enrichments are comparable and lie between 1023/m3 and 1024/m3. Possible extrapolation of the present ion irradiations to spallation source and fusion reactor conditions is shortly adressed.
Computer Simulation Study of the Effects of Copper Precipitates on Dislocation Core Structure in Ferritic Steels
Authors: Harry T. , Bacon D. J. 
Published: April 2011

AbstractThe small, coherent BCC precipitates of copper that form during fast neutron irradiation of ferritic steels are an important component of in-service irradiation hardening. Many-body interatomic potentials for the Fe-Cu alloy system have been developed and used to simulate the atomic structure of the ½<111> screw dislocation in both pure a-iron and the metastable BCC phase of copper. In iron, the core has the well-known 3-fold form of atomic disregistry. In BCC copper, however, the core structure depends on the lattice parameter. At the metastable equilibrium value, the core is similar to that in iron, but as the lattice parameter is reduced, as in a precipitate, the core becomes delocalised by transformation of the copper. Simulation of dislocated crystals containing precipitates shows that the extent of this effect depends on precipitate size. The energy changes indicate a significant dislocation pinning effect due to this dislocation-induced precipitate transformation process.
Computer Simulation Study of the Effects of Copper Solutes on Cascade Damage in Fe-Cu Alloys
Authors: Calder A. F. , Bacon D. J. 
Published: April 2011

AbstractThe production of small, coherent BCC precipitates of copper during fast neutron irradiation of ferritic steels and their apparent stability at peak hardening size are important phenomena governing in-service irradiation embrittlement. An MD model employing manybody interatomic potentials for the Fe-Cu alloy system has been developed and used to simulate the effect of displacement cascades on both dilute random solid solutions of copper and small coherent BCC copper precipitates in an oa-iron matrix. Within the timescales that can be modelled, cascades caused only small changes to the distribution of copper atoms in both the solid solution and the precipitate studies. Vacancies are observed to bind to copper solute atoms and also to accumulate in precipitates near the interface, where they are mobile. Interstitials are mobile in the solid solution matrix and two mechanisms of interstitial entrapment by precipitates are indicated.
A Comparison of Grain Boundary Monolayer Segregation Measurements Made Using Fegstem and Auger Spectroscopy
Authors: Fisher S. B. , Spellward P. , Scowen R. , Lee B. 
Published: April 2011

AbstractThe active electron optics suite at Magnox Electric's Berkeley Centre has a VG HB501 FEGSTEM and a FE-sourced Auger Microprobe (a Fisons Microlab-F) which are routinely used for grain boundary chemistry studies in a variety of highly active austenitic and ferritic steels and nickel base alloys.In a number of investigations sufficient grain boundary data have been obtained to allow a meaningful comparison between the two instruments to be made. It has been established that for the overwhelming majority of materials and conditions there exists a reasonable correlation between the two sets of compositional (on-boundary) data.This paper presents this correlation and gives a simple theoretical description justifying the relationship between the raw data from the instruments. Examples are given of materials and conditions for which the correlation cannot be established and this leads to a discussion of the usefulness of the availability of the correlation.
Effects of Ion Implantation and Temperature on Radiation-Induced Segregation In Ni-9Al Alloys
Authors: Giacobbe M. J. , Lam N. Q. , Okamoto P. R. , Zaluzec N. J. , Stubbins J. F. 
Published: April 2011

AbstractThe effects of Ne and Sc implantation on radiation-induced segregation (RIS) in Ni- 9at.%Al were studied in-situ utilizing the high-voltage electron microscopeffandem accelerator facility at Argonne National Laboratory. A highly-focused 900-keV electron beam generated radial defect fluxes which, in turn, induced the transport of Al atoms toward the center of the electronirradiated area via the inverse-Kirkendall effect. The radial segregation rate of Al atoms was monitored by measuring the diameter of the γ′-Ni3Al zone which formed in the Al-enriched area during irradiation. Ne and Sc implantation effects on RIS were investigated at 550°C, while Ne effects were also examined at 625°C to determine the influence of temperature on the ability of Ne to act as defect trapping sites, causing RIS suppression. It was found that the RIS suppression effect of Ne increased with increasing irradiation temperature, and that Sc had a small RIS suppression effect which increased with increasing Sc implantation dose. Ne bubbles which formed during implantation are believed to be responsible for its strong suppression effect.
Refinement of Irradiation and Analysis Techniques for Radiation-Induced Segregation
Authors: Allen T. R. , Cookson J. M. , Damcott D. L. , Was G. S. 
Published: April 2011

AbstractRadiation-induced segregation (RIS) has been implicated as a potential contributor to irradiation assisted stress corrosion cracking in light water reactor core components. To better understand changes to grain boundary chemistry during irradiation, RIS was measured in ultra-high purity (UHP) 304 stainless steel using Auger electron spectroscopy (AES). Variations in measured grain boundary concentration, both within a sample and between samples, are reduced by refinements in both the radiation and the AES techniques. These refinements include improvements in temperature control, uniformity of sample-to-sample dose, grain boundary acceptance criteria, amount of intergranular fracture, and amount of beam current used in analysis. AES measurements on samples irradiated at 400°C to 1.0 dpa show how implementing the technique refinements reduces the variability in the measured concentrations. Additionally, measurements from regions of ductile tearing in samples irradiated to 0.1 and 1.0 dpa at 400°C, to 1.0 dpa at 200°C, and from unirradiated samples show that sensitivity factors must be determined to obtain the most accurate measurement of grain boundary composition.
Ab Initio Pseudopotential Calculations of Carbon Impurities In SI
Authors: Zhu Jing , Diaz De La Rubia T. , Mailhiot Christian 
Published: April 2011

AbstractAb initio planewave pseudopotential method is used to study carbon diffusion and pairing in crystalline silicon. The calculation is performed with a 40 Ry planewave cutoff and 2×2×2 special k-point sampling with a supercell of 64 atoms. It is found that substitutional carbon attracts interstitial Si forming a <001> C interstitial with a large binding energy of 1.45 eV. The interstitial carbon is mobile and can migrate with a migration energy of 0.5 eV. The interstitial carbon can bind further to another substitutional carbon forming a substitutional carbon-interstitutional carbon pair with a binding energy of 1.0 eV. This model is used to understand the effect of high C concentration on the transient enhanced diffusion in Si.
Behaviour of Zirconia Based Fuel Material Under Xe Irradiation
Authors: Degueldre C. , Heimgartner P. , Ledergerber G. , Sasajima N. , Hojou K. , Muromura T. , Wang L. , Gong W. , Ewing R. 
Published: April 2011

AbstractThe behaviour of ZrO2-10%YO1.5-5%ErO1.5-( 10%ThO2) (At %) cubic solid solutions under low and high energy Xe ion irradiation up to a fluence of 1.8·1016 Xe.cm−2 was investigated by TEM. Low energy (60 keV) Xe ions did not yield amorphization. From the observed bubble formation, swelling values of less than one volume per cent were estimated to be 0.19–0.72% during irradiation at room temperature or at high temperature (925 K). Furthermore, no amorphization was obtained by Xe irradiation under extreme conditions such as high energy (1.5 MeV) Xe ion and low temperature (20 K). This confirms the robustness of this material and argues in favour of the selection of zirconia based material as an advanced nuclear fuel for plutonium disposition.
Electron Beam Driven Disordering in Small Particles
Authors: Vanfleet Richard R. , Mochel Jack 
Published: April 2011

AbstractSmall metal particles in the range of a few nanometers in diameter are seen to progressively disorder when the 100 keV electron beam of a Scanning Transmission Electron Microscope (STEM) is held stationary on the particle. The diffraction pattern of the individual particle is seen to progress from an initial array of indexable diffraction spots to a mixture of diffraction spots and amorphous-like rings and finally to rings with no persistent diffraction spots. After the electron beam is removed, the particles will recrystallize after minutes or hours. Only particles below a critical size are seen to fully disorder. We have observed this in Platinum, Palladium, Rhodium, and Iridium and based on our model of disordering process believe it is a universal effect. It has also been observed with a Platinum Ruthenium alloy. We discuss the mechanism of this disordering and the structure of the resulting disordering particle for the case of Platinum clusters.