Journal•ISSN: 0927-7056
Interface Science
Springer Science+Business Media
About: Interface Science is an academic journal. The journal publishes majorly in the area(s): Grain boundary & Grain boundary diffusion coefficient. It has an ISSN identifier of 0927-7056. Over the lifetime, 378 publications have been published receiving 7916 citations.
Topics: Grain boundary, Grain boundary diffusion coefficient, Grain boundary strengthening, Dislocation, Misorientation
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TL;DR: In this article, the authors describe the so called interfacial transition zone (ITZ) in concrete as the region of the cement paste around the aggregate particles, which is perturbed by the presence of the aggregate, and show that the higher porosity present initially is significantly diminished by the migration of ions during hydration.
Abstract: This paper describes the so called interfacial transition zone—ITZ—in concrete. This is the region of the cement paste around the aggregate particles, which is perturbed by the presence of the aggregate. Its origin lies in the packing of the cement grains against the much larger aggregate, which leads to a local increase in porosity and predominance of smaller cement particles in this region. The ITZ is region of gradual transition and is highly heterogeneous, nevertheless the average microstructural features may be measured by analysis of a large numbers of backscattered electron images of polished concrete samples. Such measurements show that the higher porosity present initially is significantly diminished by the migration of ions during hydration.
945 citations
TL;DR: In this article, the authors simulate the crystallization of highly undercooled nickel melts using a computationally efficient phase-field model together with anisotropic properties recently predicted by molecular dynamics simulations, compared to experimental data and to the predictions of a linearized solvability theory that includes both capillary and kinetic effects at the interface.
Abstract: Even though our theoretical understanding of dendritic solidification is relatively well developed, our current ability to model this process quantitatively remains extremely limited. This is due to the fact that the morphological development of dendrites depends sensitively on the degree of anisotropy of capillary and/or kinetic properties of the solid-liquid interface, which is not precisely known for materials of metallurgical interest. Here we simulate the crystallization of highly undercooled nickel melts using a computationally efficient phase-field model together with anisotropic properties recently predicted by molecular dynamics simulations. The results are compared to experimental data and to the predictions of a linearized solvability theory that includes both capillary and kinetic effects at the interface.
191 citations
TL;DR: The atomic structure of several symmetrical tilt grain boundaries (GBs) in Cu and their interaction with vacancies and interstitials as well as self-diffusion are studied by molecular statics, molecular dynamics, kinetic Monte Carlo (KMC), and other atomistic simulation methods as discussed by the authors.
Abstract: The atomic structure of several symmetrical tilt grain boundaries (GBs) in Cu and their interaction with vacancies and interstitials as well as self-diffusion are studied by molecular statics, molecular dynamics, kinetic Monte Carlo (KMC), and other atomistic simulation methods. Point defect formation energy in the GBs is on average lower than in the lattice but variations from site to site within the GB core are very significant. The formation energies of vacancies and interstitials are close to one another, which makes the defects equally important for GB diffusion. Vacancies show interesting effects such as delocalization and instability at certain GB sites. They move in GBs by simple vacancy-atom exchanges or by “long jumps” involving several atoms. Interstitial atoms can occupy relatively open positions between atoms, form split dumbbell configurations, or form highly delocalized displacement zones. They diffuse by direct jumps or by the indirect mechanism involving a collective displacement of several atoms. Diffusion coefficients in the GBs have been calculated by KMC simulations using defect jump rates determined within the transition state theory. GB diffusion can be dominated by vacancies or interstitials, depending on the GB structure. The diffusion anisotropy also depends on the GB structure, with diffusion along the tilt axis being either faster or slower than diffusion normal to the tilt axis. In agreement with Borisov's correlation, the activation energy of GB diffusion tends to decrease with the GB energy.
172 citations
TL;DR: In this article, a molecular-dynamics method for the simulation of the intrinsic migration behavior of individual, flat grain boundaries is introduced and validated for the model case of a large-planar unit-cell, high-angle(001) twist boundary in Cu.
Abstract: A molecular-dynamics method for the simulation of the intrinsicmigration behavior of individual, flat grain boundaries is introducedand validated. A constant driving force for grain-boundary migrationis generated by imposing an anisotropic elastic strain on a bicrystalsuch that the elastic-energy densities in its two halves aredifferent. For the model case of a large-planar-unit-cell, high-angle(001) twist boundary in Cu we show that an elastic strain of∼1%–4% is sufficient to drive thecontinuous, viscous movement of the boundary at temperatures wellbelow the melting point. The driving forces thus generated (at thehigh end of the experimentally accessible range) enable aquantitative evaluation of the migration process during the timeframe of 10-9 s typically accessible bymolecular-dynamics simulation. For this model high-angle grainboundary we demonstrate that (a) the drift velocity is, indeed,proportional to the applied driving force thus enabling us todetermine the boundary mobility, (b) the activation energy forgrain-boundary migration is distinctly lower than that forgrain-boundary self-diffusion or even self-diffusion in the melt and(c) in agreement with earlier simulations the migration mechanisminvolves the collective reshuffling during local disordering(“melting”) of small groups of atoms and subsequentresolidification onto the other crystal.
147 citations
TL;DR: A review of the present state of our understanding of the kinetic processes which take place on the atomic scale at the interface during crystal growth is presented in this paper, where computer simulations have played a central role in the development of this understanding.
Abstract: A brief review of the present state of our understanding of the kinetic processes which take place on the atomic scale at the interface during crystal growth is presented in this paper Computer simulations have played a central role in the development of this understanding Three aspects will be discussed: (1) There are two classes of materials based on their different modes of crystallization Molecular dynamics modeling has demonstrated that the growth rate for many simple materials is not thermally activated, but instead depends on the thermal velocity of the atoms (2) The cooperative processes which give rise to the surface roughening transition Kinetic Monte Carlo studies played a central role in the development of our understanding of how interface roughness dominates growth morphologies (3) Solute trapping in alloys Kinetic Monte Carlo simulations of alloys have led to an understanding of these kinetic effects during alloy crystallization
144 citations