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Showing 1 to 18 of 18 for “"grain boundary structure"”.
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Grain Boundary Structure in Alumina
Grain boundary microstructures in alumina ceramics are prone to show glassy phases, faceting, and some fraction of highly coincident twin-related boundaries. These separate phenomena and their inter- actions have been studied in six distinct materials of both commer- cial and experimental origin. …
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Grain-Boundary Kinetics And Nonequilibrium Grain-Boundary Structure
Microstructure of polycrystalline materials can be described as grain boundary (GB) networks; hence, GBs play major role in a wide-range of polycrystal properties. Control over GB kinetics provides effective means to tailor polycrystal properties through material processing. Understanding and …
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Computer simulation study of grain boundary structure in B2 NiAl
In an effort to understand intrinsic grain boundary brittleness, computer simulation of grain boundary structures in ordered NiAl was carried out. The considered boundaries were boundaries of low reciprocal coincident site density Σ. The structural unit model was used to obtain a general picture of …
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A study of grain boundary structure in B doped Ni3Al
A theoretical and experimental study of Grain boundary structure in B doped Ni₃Al was carried out. Geometrical modelling was done to obtain the grain boundary structure in Ll₂ compounds for different misorientations between two grains. The size of interstitial sites in these boundaries was …
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Relationship of grain boundary structure and mechanical properties of Inconel 690
… problem. SCC mechanism is dependent on the microstructure, particularly the grain boundaries, for a given alloy composition. Therefore, inhibition could be sought from an improved fundamental understanding of the structural and mechanical characteristics at the material's grain boundaries. This …
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Quantifying grain boundary structure – property relationships with atomistic simulations and data driven approaches
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms
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Atomistic Molecular Dynamics Studies of Grain Boundary Structure and Deformation Response in Metallic Nanostructures
… in this dissertation focuses on the response of grain boundaries in polycrystalline metallic nanostructures to applied strain using molecular dynamics simulations and empirical interatomic force laws. The specific goals of the work include establishing how local grain boundary structure affects …
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Effects of grain boundary structure on diffusion along [001] tilt boundaries in the Au/Ag system
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1991.
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Synthesis, Consolidation, and Mechanical Testing of Nanophase Metals
… specimens are lower than activation energy for grain boundary diffusion in microcrystalline materials. A model is proposed to explain the higher creep rate. It assumes that the specimens produced from vapor condensed powders have a higher grain boundary energy due to a higher disorder in their …
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Simulation of Bulk and Grain Boundary Diffusion in B2 NiAl
… of these are quite complex. Diffusion at the grain boundary mainly takes place through sequences of coordinated nearest neighbor jumps yielding to a rearrangement of the grain boundary structure. Two distinct mechanisms resulting in a structural unit migration of the vacancy are also …
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Effects of Carbon on Fracture Mechanisms in Nanocrystalline BCC Iron - Atomistic Simulations
… investigated. It was found that as the average grain size changes the dominant energy release mechanism also changes. Because of this the role of the intergranular carbon changes and these mechanisms compete affecting the fracture toughness differently with changing grain size. Grain boundary …
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Residual stress in nanocrystalline nickel tungsten electrodeposits
… several unique challenges due to their fine grain structure, thickness distribution, and matte surface. We employ a three-dimensional profilometry-based approach that addresses each of these complicating factors and enables quantitative analysis of residual stress with reasonable accuracy. …
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A phase field model for the gallium permeation of aluminum grain boundaries
Interfaces, such as grain boundaries, solid-liquid interfaces and solid-solid heterophase interfaces, are important features found in materials. Material properties such as fracture toughness, corrosion susceptibility and high temperature creep are influenced by grain boundary physics. The …
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Nanocrystalline alloys : enhanced strengthening mechanisms and mechanically-driven structural evolution
… as incredible strengths are predicted when grain size is reduced to the nanometer range. The vast majority of research to this point has focused on quantifying and understanding the grain size-dependence of strength, leading to the discovery of novel, grain boundary-dominated physics that …
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Recovering Grain Boundary Inclination Parameters Through Oblique Double-Sectioning
A method for the retrieval of grain boundary inclination parameters of the grain boundary character distribution by oblique double-sectioning is proposed. The method, which is similar to the recovery of the orientation distributions from sets of incomplete pole-figures, is described along with a …
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Percolation in Two-Dimensional Grain Boundary Structures and Polycrystal Property Closures
… of material properties as determined by the microstructure. The first topic involves percolation as a tool in relating the grain boundary structure to global properties such as fracture and corrosion resistance. The second investigates optimization techniques in order to find the space of values …
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The effects of dopants and complexions on grain boundary diffusion and fracture toughness in α-Al2O3
Grain boundaries often play a dominant role in determining material properties and processing, which originates from their distinct local structures, chemistry, and properties. Understanding and controlling grain boundary structure-property relationships has been an ongoing challenge that is …
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Multiscale modeling of rate dependence and size effects on nanocrystalline metallic thin films
… large fraction of atoms that lie on the grain boundaries. The grain-boundary structure differs from the crystal lattice by presenting a less ordered arrangement, which promotes diffusion-based deformation mechanisms. The small grain size also affects dislocation-based mechanisms that …