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.
Results
Showing 1 to 16 of 16 for “"Dislocation core"”.
-
Atomistic simulation of dislocation core structures in B2 NiAl
A systematic study of the core structures of (100), (110), and (111) dislocations in B2 NiAI has been conducted using atomistic simulations with an embedded atom method (EAM) potential. New flexible boundary conditions and a new method of graphic representation of dislocation core structure have …
-
Planar fault energies and dislocation core spreadings in B2 NiAl
… applications. In an effort to understand the dislocation behavior, computer simulation of the planar faults involved in the core spreadings of <100> and <111> dislocations was carried out. Seven γ-surfaces were computed for different crystallographic planes ({110}, {112}, {123}, {210}, {100}, …
-
Dislocation core energies and magnetic exchange interactions from first-principles energy density method
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-12-01
-
Deformation mechanisms in B2 aluminides: shear faults and dislocation core structures in FeAl, NiAl, CoAl and FeNiAl
… statics simulations of planar fault defects and dislocation core structures were conducted in a series of B2 aluminides with increasing ordering energy (FeAl, NiAl, CoAl). The simulation results in NiAl were compared with in-situ straining observations of dislocation motion. The dislocations …
-
Computation and application of the lattice Green function to dislocations in metals, intermetallics, and semiconductors
Dislocations are fundamental crystallographic defects that play key roles in determining material properties. The first step to understanding dislocations and being able to model them accurately is knowing their geometry. While the far-field geometry of a dislocation can be well described by …
-
Investigation of the mechanical properties and phase stability of Ti-transition metal alloys using first-principle calculations
… elastic constants, stacking fault energies and dislocation core geometries of non-dilute BCC Ti-Mo random alloys. Studies of dislocation core structures have relied on a variety of coupling techniques to manage the far-field strain fields; one very successful approach for pure materials has been …
-
Visualization and simulation of defect structures in the B2 phase of NiAl
… from simulations of B2 NiAl to study extended dislocation cores and how these cores react to nearby point defects and applied stress. Such images may be viewed as a series of images forming an animation such that a simulated quantity, such as applied stress, is cast into time. Three movies were …
-
A first principles study of defects in titanium: interaction of twin boundaries with dislocations and oxygen interstitials
Interaction between gliding dislocations and twin boundaries affects the plastic deformation of hcp metals such as titanium. In addition, oxygen greatly affects both strength and twinning in titanium. Predictive models of strength and twinning rely on understanding of the underlying atomic scale …
-
Modeling of plastic deformation due to slip-its implications in characterizing fatigue crack growth thresholds and non-Schmid behavior in transforming alloys
… scale lattice resistance against glide motion of dislocations in a perspective of laying out the dislocation core-crystal structure and applied loading interplay in particular embracing the plastic behavior in ordered shape memory alloys. The primary goal of the current work is to provide physical …
-
Strength and ductility of Mg alloys from first-principles
… method, we compute a-type basal and prismatic dislocation core structures and use these geometries to efficiently model the interaction of solutes with these cores based on solute interactions with stacking faults and strain. We show that the calculated misfit parameters are highly correlated …
-
Multi-scale investigation of vacancy-mediated diffusion of Si in Ni near an edge dislocation
… of irradiation creep is the migration of dislocations, which arises as a direct consequence of point-defect diffusion near dislocations and is also affected by the presence of solutes. In this work, we develop a multi-scale model which is able to simulate the diffusion of point-defects and …
-
New ab initio formulation of electron correlation and spin resonance
… excitation of the reconstructed 30Ê» partial dislocation in silicon. The isolated atom in the defect, or soliton, has an unusual structure involving a five-fold coordinated atom near the dislocation core. The unique electronic structure of this defect is consistent with the electron spin …
-
Hydrogen dissociative adsorption on pipeline steels in high-pressure gaseous environments
… on pipeline steel surface, i.e., grain boundary, dislocation, non-metallic inclusion are constructed. To the authors’ best knowledge, it is the first time to develop microstructure models considering surface effect. It is found that interior high angle grain boundary, edge dislocation core and the …
-
Interaction of trapped hydrogen with dislocations at low-temperature in deformed Pd
Segregation of solute atoms to dislocations occurs due to the elastic interaction with the hydrostatic stress of edge dislocations and also due to the dislocation core-solute interaction. The characteristics of the local segregation at dislocations, Cottrell atmosphere, at low temperature and low …
-
Dislocation related defects in silicon and gallium nitride.
… kinetics of carrier capture and emission from dislocations in silicon (Si) and gallium nitride (GaN) using deep level transient spectroscopy (DLTS) and Laplace DLTS (LDLTS).Laplace DLTS is a powerful tool in characterising point defect related emission, but until now it has not been used …
-
Quantitative analysis of crystal lattice and defects in nanoscale functional materials by electron diffraction
… STEM imaging is proposed and tested on a dislocation core in SiGe to visualize different types of distortion. Using the results from Cepstral STEM, a deep learning-based method is designed to differentiate different types of defects by detecting features in diffuse scattering automatically.