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in subjects: "Lattices"  
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Dislocation dynamics: simulation of plastic flow of bcc metals

Description: This is the final report for the LDRD strategic initiative entitled ''Dislocation Dynamic: Simulation of Plastic Flow of bcc Metals'' (tracking code: 00-SI-011). This report is comprised of 6 individual sections. The first is an executive summary of the project and describes the overall project goal, which is to establish an experimentally validated 3D dislocation dynamics simulation. This first section also gives some information of LLNL's multi-scale modeling efforts associated with the plast… more
Date: February 20, 2001
Creator: Lassila, D H
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Modeling of Diffusion of Plutonium in Other Metals and of Gaseous Species in Plutonium-Based Systems

Description: The problem being addressed is to establish standards for temperature conditions under which plutonium, uranium, or neptunium from nuclear wastes permeates steel, with which it is in contact, by diffusion processes. The primary focus is on plutonium because of the greater difficulties created by the peculiarities of face-centered-cubic-stabilized (delta) plutonium (the form used in the technology generating the waste). Temperature is the key controllable diffusion process, i.e., temperature con… more
Date: June 1, 2001
Creator: Cooper, Bernard R. & Fernando, Gayanath W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Boundary Conditions for Dislocation Dynamics Simulations and Stage 0 of BCC Metals at Low Temperature

Description: In order to study the dislocation density evolution of body centered cubic (bcc) crystals at low temperature by dislocation dynamics (DD) simulations, we investigated carefully three different boundary conditions (BC) for DD, i.e., the quasi-free surface BC, the flux-balanced BC, and the periodic BC. The latter two BCs can account for the dislocation loss from the boundary of the finite simulation box. PBC can also eliminate the influence of surfaces and improve the line connectivity. We have f… more
Date: May 1, 2001
Creator: Tang, M & Kubin, L P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Atomistic Simulation of Dislocation-Defect Interactions in Cu

Description: The mechanisms of dislocation-defect interactions are of practical importance for developing quantitative structure-property relationships, mechanistic understanding of plastic flow localization and predictive models of mechanical behavior in metals under irradiation. In copper and other face centered cubic metals, high-energy particle irradiation produces hardening and shear localization. Post-irradiation microstructural examination in Cu reveals that irradiation has produced a high number den… more
Date: January 1, 2001
Creator: Wirth, B D; Bulatov, V V & Diaz de la Rubia, T
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

An Interferometric Electron Ruler With Picometer Accuracy in Gauaging Lattice Displacement.

Description: We report a novel technique to accurately measure interfacial lattice displacement by forming an electron probe close to a specimen in a manner similar to that originally proposed by Gabor to record a hologram. This method is based on the quantitative analysis of the interference pattern of shadow images in coherent electron diffraction. The approach is unique in that there are no adjustable microscope parameters, the contrast is strong even when the fault is viewed edge-on, and a large number … more
Date: August 5, 2001
Creator: Wu, L.; Zhu, Y. & Tafto, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Probing toward the solid state plasma accelerator frontier using channeling radiation measurements at the Fermilab A0 photoinjector

Description: Plasmas offer the possibility of high acceleration gradients. An intriguing suggestion is to use the higher plasma densities possible in solids to get extremely high gradients. Although solid state plasmas might produce high gradients they would pose daunting problems. Crystal channeling has been suggested as one mechanism to address these challenges. There is no experimental or theoretical guidance on channeling in intense electron and laser beams. A high density plasma in a crystal lattice co… more
Date: March 28, 2001
Creator: Richard A. Carrigan, Jr. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Micromechanical Uncooled Photon Detectors

Description: Recent advances in micro-electro-mechanical systems (MEMS) have led to the development of uncooled infrared detectors operate as micromechanical thermal detectors or micromechanical quantum detectors. The authors report on a new method for photon detection using electronic (photo-induced) stresses in semiconductor microstructures. Photo-induced stress in semiconductor microstructures, is caused by changes in the charge carrier density in the conduction band and photon detection results from the… more
Date: September 4, 2001
Creator: Datskos, P. G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

USING A MULTI-DISCIPLINARY APPROACH, THE FIRST ELECTRON BACKSCATTERED KIKUCHI PATTERNS WERE CAPTURES FOR A PU ALLOY

Description: Microstructural characterization of plutonium by electron backscattered diffraction (EBSD) has been previously elusive primarily because of the extreme toxicity and surface oxidation rates associated with plutonium metal. In this work, initial electron backscattered diffraction pattern (EBSP) observations of a plutonium-gallium (Pu-Ga) alloy were made. Samples were prepared using standard metallographic and electropolishing techniques that were performed inside gloveboxes and/or an open front h… more
Date: June 1, 2001
Creator: BOEHLERT, C. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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