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Grain Boundary Sliding

About: Grain Boundary Sliding is a research topic. Over the lifetime, 3844 publications have been published within this topic receiving 93077 citations.


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Journal ArticleDOI
05 Sep 2003-Science
TL;DR: Using molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper, it is shown that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15 nanometers.
Abstract: We used molecular dynamics simulations with system sizes up to 100 million atoms to simulate plastic deformation of nanocrystalline copper. By varying the grain size between 5 and 50 nanometers, we show that the flow stress and thus the strength exhibit a maximum at a grain size of 10 to 15 nanometers. This maximum is because of a shift in the microscopic deformation mechanism from dislocation-mediated plasticity in the coarse-grained material to grain boundary sliding in the nanocrystalline region. The simulations allow us to observe the mechanisms behind the grain-size dependence of the strength of polycrystalline metals.

1,289 citations

Journal ArticleDOI
01 Apr 1971
TL;DR: In this paper, the problem of sliding at a nonplanar grain boundary is considered in detail, and the results give solutions to the following problems: 1) How much sliding occurs in a polycrystal when neither diffusive flow nor dislocation motion is possible? 2) What is the sliding rate at a wavy or stepped grain boundary when diffusional flow of matter occurs? 3) How is the rate of diffusional creep in polycrystals in which grain boundaries slide? 4) how is this creep rate affected by grain shape, and grain boundary migration? 5)
Abstract: The problem of sliding at a nonplanar grain boundary is considered in detail. The stress field, and sliding displacement and velocity can be calculated at a boundary with a shape which is periodic in the sliding direction (a wavy or stepped grain boundary): a) when deformation within the crystals which meet at the boundary is purely elastic, b) when diffusional flow of matter from point to point on the boundary is permitted. The results give solutions to the following problems. 1) How much sliding occurs in a polycrystal when neither diffusive flow nor dislocation motion is possible? 2) What is the sliding rate at a wavy or stepped grain boundary when diffusional flow of matter occurs? 3) What is the rate of diffusional creep in a polycrystal in which grain boundaries slide? 4) How is this creep rate affected by grain shape, and grain boundary migration? 5) How does an array of discrete particles influence the sliding rate at a grain boundary and the diffusional creep rate of a polycrystal? The results are compared with published solutions to some of these problems.

1,101 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings is addressed. And the properties of transition metal nitride nanocrystine films formed by ion beam assisted deposition process.
Abstract: In recent years, near-nano (submicron) and nanostructured materials have attracted increasingly more attention from the materials community. Nanocrystalline materials are characterized by a microstructural length or grain size of up to about 100 nm. Materials having grain size of ∼0.1 to 0.3 μm are classified as submicron materials. Nanocrystalline materials exhibit various shapes or forms, and possess unique chemical, physical or mechanical properties. When the grain size is below a critical value (∼10–20 nm), more than 50 vol.% of atoms is associated with grain boundaries or interfacial boundaries. In this respect, dislocation pile-ups cannot form, and the Hall–Petch relationship for conventional coarse-grained materials is no longer valid. Therefore, grain boundaries play a major role in the deformation of nanocrystalline materials. Nanocrystalline materials exhibit creep and super plasticity at lower temperatures than conventional micro-grained counterparts. Similarly, plastic deformation of nanocrystalline coatings is considered to be associated with grain boundary sliding assisted by grain boundary diffusion or rotation. In this review paper, current developments in fabrication, microstructure, physical and mechanical properties of nanocrystalline materials and coatings will be addressed. Particular attention is paid to the properties of transition metal nitride nanocrystalline films formed by ion beam assisted deposition process.

832 citations

Journal ArticleDOI
TL;DR: In this article, the mechanisms of deformation and damage evolution in electrodeposited, fully dense, nanocrystalline Ni with an average grain size of ~30 nm and a narrow grain size distribution were investigated by recourse to (i) tensile tests performed in situ in the transmission electron microscope and (ii) microscopic observations made at high resolution following ex situ deformation induced by compression, rolling and nanoindentation.

689 citations

Journal ArticleDOI
TL;DR: In this article, a constitutive equation based on these experimental results that includes flow laws for these four creep mechanisms is described. But this equation is in excellent agreement with published laboratory creep data for coarse-grained samples at high temperatures.
Abstract: Creep experiments on fine-grained ice reveal the existence of three creep regimes: (1) a dislocation creep regime; (2) a superplastic flow regime in which grain boundary sliding is an important deformation process; and (3) a basal slip creep regime in which the strain rate is limited by basal slip. Dislocation creep in ice is likely climb-limited, is characterized by a stress exponent of 4.0, and is independent of grain size. Superplastic flow is characterized by a stress exponent of 1.8 and depends inversely on grain size to the 1.4 power. Basal slip limited creep is characterized by a stress exponent of 2.4 and is independent of grain size. A fourth creep mechanism, diffusional flow, which usually occurs at very low stresses, is inaccessible at practical laboratory strain rates even for our finest grain sizes of approximately 3 micrometers. A constitutive equation based on these experimental results that includes flow laws for these four creep mechanisms is described. This equation is in excellent agreement with published laboratory creep data for coarse-grained samples at high temperatures. Superplastic flow of ice is the rate-limiting creep mechanism over a wide range of temperatures and grain sizes at stresses less than or equal to 0.1 MPa, conditions which overlap those occurring in glaciers, ice sheets, and icy planetary interiors.

608 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202351
202275
2021128
2020140
2019113
2018105