Iron-Copper-Nickel Many-Body Potential Consistent With Thermodynamics

2009 ◽  
Author(s):  
Giovanni Bonny ◽  
Roberto C. Pasianot ◽  
Nicolas Castin ◽  
Dmitry Terentyev ◽  
Lorenzo Malerba
Keyword(s):  
Large Scale ◽  
Kinetic Monte Carlo ◽  
Atomistic Simulations ◽  
Model Alloy ◽  
Precipitate Size ◽  
Many Body ◽  
Cu Alloy ◽  
Kinetic Monte Carlo Simulations ◽  
Body Potential ◽  
First Time

The Fe-Cu-Ni ternary alloy is of interest for nuclear applications because Cu and Ni are considered to have major effects on the embrittlement under irradiation of reactor pressure vessel steels. To improve our understanding on this phenomenon, large scale atomistic simulations in this model alloy are desirable. For this purpose we develop a ternary Fe-Cu-Ni many-body potential consistent with thermodynamics is developed for the first time. The potential was validated using molecular static and atomistic kinetic Monte Carlo simulations and a qualitative agreement with experiments was established. In particular, Cu precipitates were found to be enriched by Ni on the precipitate surface. Also, the effects diluting the Fe-Cu alloy by Ni on mean precipitate size and density showed similar trends as observed in experiments; i.e. no effect of Ni on the mean precipitate size and an increase in the maximum precipitate density due to the addition of Ni. In absolute terms, agreement with experiment is poor due to the limited box size used in the simulations, as correspondingly discussed.

scholarly journals Kinetic Monte Carlo Simulation of Clustering in an Al-Mg-Si-Cu Alloy

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4523
Author(s):  
Qilu Ye ◽  
Jianxin Wu ◽  
Jiqing Zhao ◽  
Gang Yang ◽  
Bin Yang
Keyword(s):  
Activation Energy ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Complex Interaction ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Simulation Results ◽  
Small Clusters ◽  
First Time

The mechanism of the clustering in Al-Mg-Si-Cu alloys has been a long-standing controversial issue. Here, for the first time, the mechanism of the clustering in the alloy was investigated by a Kinetic Monte Carlo (KMC) approach. In addition, reversion aging (RA) was carried out to evaluate the simulation results. The results showed that many small-size clusters formed rapidly in the early stages of aging. With the prolongation of aging time, the clusters merged and grew. The small clusters formed at the beginning of aging in Al-Mg-Si-Cu alloy were caused by initial vacancies (quenching vacancies). The merging and decomposition of the clusters were mainly caused by the capturing of vacancies, and the clusters had a probability to decompose before reaching a stable size. After repeated merging and decomposition, the clusters reach stability. During RA, the complex interaction between the cluster merging and decomposition leaded to the partial irregular change of the hardness reduction and activation energy.

Effects of Crystalline Microstructure on Epitaxial Morphology

1995 ◽  
Vol 399 ◽  
Author(s):  
Fereydoon Family ◽  
Jacques G. Amar
Keyword(s):  
Crystal Structure ◽  
Epitaxial Growth ◽  
Large Scale ◽  
Kinetic Monte Carlo ◽  
Island Size ◽  
The Past ◽  
Stages Of Growth ◽  
Kinetic Monte Carlo Simulations ◽  
Crystalline Microstructure ◽  
Good Agreement

ABSTRACTIn the past simulations of epitaxial growth have used solid-on-solid (SOS) models to simulate the crystalline structure of both the substrate and the growing crystal. These models have produced results in the early stages of growth in good agreement with experiments for a number of different quantities, including the island density and the island size distribution. For multilayer growth, however, there exists a competition between microscopic effects such as the Ehrlich-Schwoebel step barrier and the crystalline microstructure. Therefore, the crystal structure and geometry are important in determining the dynamics and evolution of epitaxial structure and morphology. We present the results of large-scale realistic kinetic Monte-Carlo simulations of multilayer epitaxial growth on fcc(100) and bcc(100) surfaces. The influence of crystal structure on the formation and coarsening of mounds and facets is discussed. We also discuss and compare our results with recent experiments.

Global Optimization of Tersoff Clusters Using Differential Evolution with Inexact Line Search

2011 ◽  
Vol 48-49 ◽  
pp. 565-568
Author(s):  
Yang Jun He ◽  
Gui Jun Zhang
Keyword(s):  
Global Optimization ◽  
Differential Evolution ◽  
Ground State ◽  
Large Scale ◽  
Line Search ◽  
Differential Evolution Algorithm ◽  
Many Body ◽  
Inexact Line Search ◽  
Body Potential ◽  
Semi Empirical

Differential Evolution with Inexact Line Search (DEILS) is proposed to determination of the ground-state geometry of atom clusters. DEILS algorithm adopts probabilistic inexact line search method in acceptance rule of differential evolution to accelerate the convergence as the region of global minimum is approached. More realistic many-body potential energy functions, namely the Tersoff and Tersoff-like semi-empirical potentials for silicon, are considered. Numerical studies indicate that the new algorithm is considerably faster and more reliable than original differential evolution algorithm, especially for large-scale global optimization problem of MBP6/Si(C). Moreover, some ground-state solutions, which are superior to the known best solution given in literature, are reported.

Computer Simulation of Microstructure Evolution of Fe-Cu Alloy during Thermal Ageing

2006 ◽  
Vol 306-308 ◽  
pp. 917-922
Author(s):  
Akiyuki Takahashi ◽  
Naoki Soneda ◽  
Masanori Kikuchi
Keyword(s):  
Computer Simulation ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Numerical Models ◽  
Kinetic Monte Carlo ◽  
Thermal Ageing ◽  
Vacancy Clusters ◽  
Cu Alloy ◽  
Long Time ◽  
Kinetic Monte Carlo Simulations

This paper describes a computer simulation of thermal ageing process in Fe-Cu alloy. In order to perform accurate numerical simulation, firstly, we make numerical models of the diffusion and dissociation of Cu and Cu-vacancy clusters. This modeling was performed with kinetic lattice Monte Carlo method, which allows us to perform long-time simulation of vacancy diffusion in Fe-Cu dilute alloy. The model is input to the kinetic Monte Carlo method, and then, we performed the kinetic Monte Carlo simulation of the thermal ageing in the Fe-Cu alloy. The results of the KMC simulations tell us that the our new models describes well the rate and kinetics of the diffusion and dissociation of Cu and Cu-vacancy clusters, and works well in the kinetic Monte Carlo simulations. Finally, we discussed the further application of these numerical models.

Experimental and theoretical investigation of the order-disorder transformation in Ni3Al

1993 ◽  
Vol 8 (10) ◽  
pp. 2504-2509 ◽  
Author(s):  
Francesco Cardellini ◽  
Fabrizio Cleri ◽  
Giorgio Mazzone ◽  
Amelia Montone ◽  
Vittorio Rosato
Keyword(s):  
Atomistic Simulations ◽  
Many Body ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Disordered Phase ◽  
Migration Mechanism ◽  
Extended Range ◽  
The Stability ◽  
Body Potential ◽  
Scanning Electron

The crystalline disordered phase obtained by mechanical alloying of elemental 75 at. % Ni and 25 at. % Al powders has been investigated. The stability of this phase with respect to the thermal reordering process leading to the L12 structure has been analyzed by means of x-ray diffractometry, scanning electron microscopy, and differential scanning calorimetry. Atomistic simulations on an Ni3Al model, reproduced via molecular dynamics using a many-body potential, have been used to interpret experimental data. The ordering transformation takes place in an extended range of temperature (from 320 to 600 °C) and occurs simultaneously with the release of internal strain. Numerical simulations performed under different conditions show that the activation energy of the Ni-vacancy migration mechanism responsible for the ordering process depends on the local state of strain, thus suggesting an explanation for the considerable lowering of this energy in samples obtained by ball milling.

Accurate Interatomic Potentials for Ni, Al and Ni3Al

1986 ◽  
Vol 82 ◽  
Author(s):  
Arthur F. Voter ◽  
Shao Ping Chen
Keyword(s):  
Interatomic Potential ◽  
Alloy System ◽  
Atomistic Simulations ◽  
Al Alloy ◽  
Interatomic Potentials ◽  
Many Body ◽  
Fitting Procedure ◽  
Crack Tips ◽  
Computational Dependence ◽  
Body Potential

ABSTRACTTo obtain meaningful results from atomistic simulations of materials, the interatomic potentials must be capable of reproducing the thermodynamic properties of the system of interest. Pairwise potentials have known deficiencies that make them unsuitable for quantitative investigations of defective regions such as crack tips and free surfaces. Daw and Baskes [Phys. Rev. B 29, 6443 (1984)] have shown that including a local “volume” term for each atom gives the necessary many-body character without the severe computational dependence of explicit n-body potential terms. Using a similar approach, we have fit an interatomic potential to the Ni3Al alloy system. This potential can treat diatomic Ni2, diatomic Al2, fcc Ni, fcc Al and L12 Ni3Al on an equal footing. Details of the fitting procedure are presented, along with the calculation of some properties not included in the fit.

Scheming

2018 ◽  
Author(s):  
Seán Damer
Keyword(s):  
Social Class ◽  
Housing Policy ◽  
Large Scale ◽  
Class Structure ◽  
Local Council ◽  
Housing Scheme ◽  
Post War ◽  
First Time ◽  
The Voice ◽  
House Building

This book seeks to explain how the Corporation of Glasgow, in its large-scale council house-building programme in the inter- and post-war years, came to reproduce a hierarchical Victorian class structure. The three tiers of housing scheme which it constructed – Ordinary, Intermediate, and Slum-Clearance – effectively signified First, Second and Third Class. This came about because the Corporation uncritically reproduced the offensive and patriarchal attitudes of the Victorian bourgeoisie towards the working-class. The book shows how this worked out on the ground in Glasgow, and describes the attitudes of both authoritarian housing officials, and council tenants. This is the first time the voice of Glasgow’s council tenants has been heard. The conclusion is that local council housing policy was driven by unapologetic considerations of social class.

Effective Interactions Approach to Phase Stability in Alloys Under Irradiation

1998 ◽  
Vol 538 ◽  
Author(s):  
Raúl A. Enrique ◽  
Pascal Bellon
Keyword(s):  
Phase Diagram ◽  
Phase Stability ◽  
Kinetic Monte Carlo ◽  
Theoretical Frameworks ◽  
Effective Interactions ◽  
Dynamical Phase ◽  
Thermodynamic Potentials ◽  
Simple Kinetic Model ◽  
Kinetic Monte Carlo Simulations ◽  
Competing Dynamics

AbstractPhase stability in alloys under irradiation is studied considering effective thermodynamic potentials. A simple kinetic model of a binary alloy with phase separation is investigated. Time evolution in the alloy results from two competing dynamics: thermal diffusion, and irradiation induced ballistic exchanges. The dynamical (steady state) phase diagram is evaluated exactly performing Kinetic Monte Carlo simulations. The solution is then compared to two theoretical frameworks: the effective quasi-interactions model as proposed by Vaks and Kamishenko, and the effective free energy model as proposed by Martin. New developments of these models are proposed to allow for quantitative comparisons. Both theoretical frameworks yield fairly good approximations to the dynamical phase diagram.

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