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.

scholarly journals Simulations of long time scale dynamics using the dimer method

2001 ◽  
Vol 677 ◽  
Author(s):  
Graeme Henkelman ◽  
Hannes Jónsson
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Transition State ◽  
Time Scale ◽  
Transition State Theory ◽  
Kinetic Monte Carlo ◽  
Chem Phys ◽  
State Theory ◽  
Kinetic Monte Carlo Method ◽  
Long Time

We have carried out long time scale simulations where the “dimer method” [G. Henkelman and H. Jónsson, J. Chem. Phys. 111, 7010 (1999)] is used to find the mechanism and estimate the rate of transitions within harmonic transition state theory and time is evolved by using the kinetic Monte Carlo method. Unlike traditional applications of kinetic Monte Carlo, the atoms are not assigned to lattice sites and a list of all possible transitions does not need to be specified beforehand. Rather, the relevant transitions are found on the y during the simulation. An application to the diffusion and island formation of Al adatoms on an Al(100) surface is presented.

Examination of the Effect of Vacancy Detachment Rates on Kinetic Monte Carlo Simulations of bcc Metals

MRS Advances ◽  
2016 ◽  
Vol 1 (35) ◽  
pp. 2489-2494 ◽  
Author(s):  
Richard T Hoffman ◽  
Alexander P Moore ◽  
Chaitanya S Deo
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Void Formation ◽  
Binding Energies ◽  
Size Dependent ◽  
Bcc Metals ◽  
Bcc Lattice ◽  
Long Time ◽  
Kinetic Monte Carlo Simulations ◽  
Dynamics Simulations

ABSTRACTA Kinetic Monte Carlo simulation, using a modified version of the SPPARKS code, of simple defects and complex vacancy clusters was run on a bcc lattice. In this simulation the complexity of void formation was varied by introducing a detachment rate for individual vacancies leaving the void and either treating this value as constant for all size voids or having this value be dependent on the size of the void. Molecular Dynamics simulations were used to determine the binding energies of vacancies for voids of varying size. The simulation was then run over long time periods to determine the number of defects in the simulation under irradiation conditions. It was found that the additional complexity of size dependent void detachment rates had little effect on the defect concentrations and thus a constant barrier should be sufficient for simulations of voids in bcc metals.

Adaptive kinetic Monte Carlo simulations of surface segregation in PdAu nanoparticles

Nanoscale ◽  
2019 ◽  
Vol 11 (21) ◽  
pp. 10524-10535 ◽  
Author(s):  
Lei Li ◽  
Xinyu Li ◽  
Zhiyao Duan ◽  
Randall J. Meyer ◽  
Rob Carr ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Catalytic Activity ◽  
Monte Carlo Method ◽  
Surface Segregation ◽  
Bimetallic Nanoparticles ◽  
Kinetic Monte Carlo ◽  
Core Shell ◽  
Kinetic Monte Carlo Method ◽  
Kinetic Monte Carlo Simulations ◽  
Pdau Nanoparticles

Surface segregation in bimetallic nanoparticles is critically important for their catalytic activity. Here, we use the adaptive kinetic Monte Carlo method to model the segregation dynamics in PdAu NPs over experimentally relevant time scales and demonstrate thermodynamically unfavorable Au@Pd core–shell and alloy NPs can be kinetically trapped at low temperature.

scholarly journals A derivation and scalable implementation of the synchronous parallel kinetic Monte Carlo method for simulating long-time dynamics

2017 ◽  
Vol 219 ◽  
pp. 246-254 ◽  
Author(s):  
Hye Suk Byun ◽  
Mohamed Y. El-Naggar ◽  
Rajiv K. Kalia ◽  
Aiichiro Nakano ◽  
Priya Vashishta
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Kinetic Monte Carlo ◽  
Kinetic Monte Carlo Method ◽  
Time Dynamics ◽  
Long Time ◽  
Long Time Dynamics

Probabilistic multiscale modeling of fracture in heterogeneous materials and structures

2020 ◽  
Vol 86 (7) ◽  
pp. 45-54
Author(s):  
A. M. Lepikhin ◽  
N. A. Makhutov ◽  
Yu. I. Shokin
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Fracture Mechanics ◽  
Multiscale Modeling ◽  
Virtual Work ◽  
Numerical Models ◽  
Heterogeneous Materials ◽  
Heterogeneous Structure ◽  
Generalized Coordinates ◽  
Heterogeneous Structures

The probabilistic aspects of multiscale modeling of the fracture of heterogeneous structures are considered. An approach combining homogenization methods with phenomenological and numerical models of fracture mechanics is proposed to solve the problems of assessing the probabilities of destruction of structurally heterogeneous materials. A model of a generalized heterogeneous structure consisting of heterogeneous materials and regions of different scales containing cracks and crack-like defects is formulated. Linking of scales is carried out using kinematic conditions and multiscale principle of virtual forces. The probability of destruction is formulated as the conditional probability of successive nested fracture events of different scales. Cracks and crack-like defects are considered the main sources of fracture. The distribution of defects is represented in the form of Poisson ensembles. Critical stresses at the tops of cracks are described by the Weibull model. Analytical expressions for the fracture probabilities of multiscale heterogeneous structures with multilevel limit states are obtained. An approach based on a modified Monte Carlo method of statistical modeling is proposed to assess the fracture probabilities taking into account the real morphology of heterogeneous structures. A feature of the proposed method is the use of a three-level fracture scheme with numerical solution of the problems at the micro, meso and macro scales. The main variables are generalized forces of the crack propagation and crack growth resistance. Crack sizes are considered generalized coordinates. To reduce the dimensionality, the problem of fracture mechanics is reformulated into the problem of stability of a heterogeneous structure under load with variations of generalized coordinates and analysis of the virtual work of generalized forces. Expressions for estimating the fracture probabilities using a modified Monte Carlo method for multiscale heterogeneous structures are obtained. The prospects of using the developed approaches to assess the fracture probabilities and address the problems of risk analysis of heterogeneous structures are shown.

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