Multiscale Modelling of the Ageing Kinetics of a 2D Deposit

2011 ◽  
Vol 172-174 ◽  
pp. 664-669 ◽  
Author(s):  
Fabienne Berthier ◽  
Emile Maras ◽  
Isabelle Braems ◽  
Bernard Legrand
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Kinetic Monte Carlo ◽  
Interfacial Free Energy ◽  
Precipitation Kinetics ◽  
Coalescence Model ◽  
Time Space ◽  
Constrained Equilibrium ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetics Of

We compare three models of 2D precipitation kinetics that give access to different time-space scales. Kinetic Monte Carlo simulations (KMC), cluster dynamics (CD) and nucleation-growth-coalescence model (NGCM), based on a same atomic model, lead to an excellent agreement as long as the interfacial free energy is evaluated accurately and the interaction between diffusion fields is taken into account in the CD. The NGCM model noticeably improves the previous approaches of the same kind by using a constrained-equilibrium hypothesis to describe the solid solution. Moreover, in the coalescence regime, we show that CD leads to cluster distributions that are wider and more symmetric than the LSW distribution due to the probabilistic feature of the growth law of a cluster, that makes it differ from the purely deterministic NGCM approach.

Vacancy-Mediated Diffusion and Diffusion-Controlled Processes in Ordered Binary Intermetallics by Kinetic Monte Carlo Simulations

2021 ◽  
Vol 29 ◽  
pp. 95-115
Author(s):  
Rafal Kozubski ◽  
Graeme E. Murch ◽  
Irina V. Belova
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Simulation Studies ◽  
Self Diffusion ◽  
Monte Carlo Techniques ◽  
Diffusion Controlled ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetic Effects ◽  
Kinetics Of ◽  
And Diffusion

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

Kinetics of palladium particles on LiNbO3: an origin of the polarization-dependent catalysis

2012 ◽  
Vol 1397 ◽  
Author(s):  
Seungchul Kim ◽  
Michael Rutenberg Schoenberg ◽  
Andrew M. Rappe
Keyword(s):  
Monte Carlo ◽  
Catalytic Activity ◽  
Kinetic Monte Carlo ◽  
Polarization Direction ◽  
Atomic Structures ◽  
Negative Surface ◽  
Kinetic Monte Carlo Simulations ◽  
Pd Clusters ◽  
Palladium Particles ◽  
Kinetics Of

ABSTRACTUsing ab-initio calculations and kinetic Monte Carlo simulations, we demonstrate that the deposition geometries of palladium are strongly dependent on the polarization direction of the LiNbO3 substrate. Different stoichiometries and atomic structures of the positively and the negatively polarized substrates cause substantially different bonding configurations of palladium and energy barriers for the movement of Pd clusters. Our simulations predict that palladium atoms form bulky clusters on the positive surface, while they are deposited in a dispersed or planar manner on the negative surface at moderate temperature. We suggest that Inoue and coworkers’ observation [J. Phys. Chem.88, 1148 (1984)] that the catalytic activity of palladium depends on polarization direction of LiNbO3 substrate is, at least in part, due to differences in the geometric structures of palladium and the LiNbO3 surface.

TEM Study of Precipitation Kinetics of Epsilon Copper in HSLA (A710) Steel

1985 ◽  
Vol 43 ◽  
pp. 330-331
Author(s):  
C.S. Pande ◽  
S. Smith ◽  
L.E. Richards
Keyword(s):  
Solid Solution ◽  
Small Angle Neutron Scattering ◽  
Ferritic Steel ◽  
Precipitation Kinetics ◽  
Aging Condition ◽  
Subsequent Aging ◽  
Lattice Constants ◽  
The Matrix ◽  
Bcc Structure ◽  
Kinetics Of

A710 steel is an agehardening ferritic steel containing 1.2% (wt) copper. After austenitization and quenching at 1100°C, the copper is retained in solid solution. In subsequent aging this copper appears as fine precipitates. It is postulated that these precipitates when initially formed have bcc structure and are coherent with the matrix. They are then very difficult to detect by conventional TEM presumably because of small mismatch between the lattice constants of the copper precipitates and the matrix. Subsequent aging transforms the copper precipitates into incoherent precipitates which can be easily detected by conventional TEM. We have characterized the precipitate kinetics of these incoherent copper precipitates by TEM. These specimens were also characterized by small angle neutron scattering and hardening measurements to detect coherent copper precipitates. A combination of the three techniques has been used to study the precipitation kinetics of copper precipitates. Our results indicate that the transition from coherent to incoherent precipitation is continuous and presumably depends on the size of the precipitate rather than on the actual aging condition.

Stochastic Statistical Theory of Precipitation in Metastable Alloys with Application to Fe-Cu and Fe-Cu-Mn Alloy Systems

2011 ◽  
Vol 172-174 ◽  
pp. 1146-1155
Author(s):  
Konstantin Khromov ◽  
Frédéric Soisson ◽  
Andrey Stroev ◽  
Valentin Vaks
Keyword(s):  
Statistical Approach ◽  
Kinetic Monte Carlo ◽  
Great Sensitivity ◽  
Computationally Efficient ◽  
Nucleation Stage ◽  
Cu Alloys ◽  
Kinetics Of Decomposition ◽  
Kinetic Monte Carlo Simulations ◽  
Metastable Alloys ◽  
Kinetics Of

The consistent and computationally efficient stochastic statistical approach is suggestedto study kinetics of decomposition of metastable alloys. An important parameter of the theory is thesize of locally equilibrated regions at the nucleation stage which is estimated using the ``maximumthermodynamic gain'' principle suggested. For several realistic models of Fe-Cu alloys studied, the re-sults obtained agree well with kinetic Monte Carlo simulations. Application of methods developed tostudies of decomposition of Fe-Cu-Mn alloys revealed a great sensitivity of evolution to both the con-figurational and kinetic interatomic interactions in an alloy. Using for these interactions the availablefirst-principle and CALPHAD estimates, we can well reproduce the peculiar features of decomposi-tion of Fe-Cu-Mn alloys observed in experiments.

scholarly journals Kinetic lattice Monte-Carlo simulations on the ordering kinetics of free and supported FePt L10-nanoparticles

2011 ◽  
Vol 2 ◽  
pp. 40-46 ◽  
Author(s):  
Michael Müller ◽  
Karsten Albe
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Kinetic Monte Carlo ◽  
Bulk Diffusion ◽  
Particle Volume ◽  
Ordering Kinetics ◽  
Kinetic Monte Carlo Simulations ◽  
Thermodynamic Driving Force ◽  
Interface Segregation ◽  
Kinetics Of

The ordering kinetics in free and supported L10 nanoparticles was studied by means of lattice-based kinetic Monte-Carlo simulations. Starting from a fully disordered particle of Wulff shape, the simulations show that the nucleation of ordered domains is starting quickly on various (100) facets but is retarded in the particle volume due to the lack of vacancies compared with a thin film geometry. If a substrate is present, we do not find significant differences in the ordering behavior. This holds true, even if we impose a massively increased thermodynamic driving force for interface segregation, because the nucleation of ordered domains on free facets is significantly faster than the bulk diffusion of the segregating species to the interface. In cases where wetting of the substrate or surface facetting occurs, we find that diffusional atomic motion on the surface goes along with an enhanced long-range order.

Mound Formation, Coarsening and Instabilities in Epitaxial Growth

1998 ◽  
Vol 05 (03n04) ◽  
pp. 851-864 ◽  
Author(s):  
Jacques G. Amar ◽  
Fereydoon Family
Keyword(s):  
Epitaxial Growth ◽  
Kinetic Monte Carlo ◽  
Realistic Model ◽  
Island Nucleation ◽  
Homoepitaxial Growth ◽  
Coarsening Behavior ◽  
Kinetic Monte Carlo Simulations ◽  
Temperature Deposition ◽  
Mound Formation ◽  
Kinetics Of

An introductory review of the central ideas in the kinetics of multilayer epitaxial growth is presented. A realistic model for multilayer homoepitaxial growth on fcc(100) and bcc(100) surfaces which takes into account the correct crystal structure is discussed. The effects of instabilities which lead to mound formation and coarsening are discussed, and a unified picture of the effects of attractive and repulsive interactions at ascending and descending steps on surface morphology and island nucleation is presented. An accurate prediction of the observed mound angle for Fe/Fe(100) deposition is obtained analytically and by kinetic Monte Carlo simulations. The general dependence of the mound angle and mound coarsening behavior on the temperature, deposition rate and strength of the step barrier in bcc(100) and fcc(100) growth is also presented, and compared with recent experiments.

Kinetic Monte Carlo simulations of heterogeneously catalyzed oxidation reactions

2014 ◽  
Vol 4 (3) ◽  
pp. 583-598 ◽  
Author(s):  
Franziska Hess ◽  
Herbert Over
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Kinetic Monte Carlo ◽  
Surface Species ◽  
Lateral Interactions ◽  
Oxidation Reactions ◽  
Oxidation Of Co ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetics Of ◽  
Catalyzed Oxidation

In this perspective, we focus on the catalyzed oxidation of CO and HCl over the model catalyst RuO2(110) and how the kinetics of these reactions can only properly be modeled by kinetic Monte Carlo (kMC) simulations when lateral interactions of the surface species are taken into account.

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