Simulation of Interstitial Atom Diffusion in FCC Metals with Point Defects

2005 ◽  
Vol 237-240 ◽  
pp. 1275-1280
Author(s):  
Liudmila V. Selezneva ◽  
Andrei V. Nazarov
Keyword(s):  
Monte Carlo ◽  
Diffusion Coefficient ◽  
Point Defects ◽  
Monte Carlo Methods ◽  
Interstitial Atom ◽  
Activation Barrier ◽  
Atom Diffusion ◽  
Fcc Metals ◽  
Different Temperatures ◽  
Fcc Metal

This work is devoted to simulation of interstitial atom diffusion in fcc metals with point defects. We used the molecular static and the Monte Carlo methods. An activation barrier set for different configurations of the carbon–vacancy complexes is simulated by the method of the molecular static (MS). Then we calculate atom jump rates for these configurations. The simulation of the carbon and vacancy migration in an fcc metal is realized on the basis of obtained atom jump rates by using the Monte-Carlo (MC) method. In particular, the calculations were made for the system of the nickel-carbon. In the result of that interstitial atom diffusion coefficient has been obtained at different temperatures.

THE DIFFUSION IN FCC BINARY INTERSTITIAL ALLOY

2020 ◽  
Vol 65 (10) ◽  
pp. 18-23
Author(s):  
Hoc Nguyen Quang ◽  
Loan Pham Thi Thanh ◽  
Viet Nguyen Tuan ◽  
Le Nguyen Ngoc
Keyword(s):  
Diffusion Coefficient ◽  
Moment Method ◽  
Interstitial Atom ◽  
Diffusion Theory ◽  
Correlation Factor ◽  
Statistical Moment ◽  
Analytic Expressions ◽  
Fcc Metal ◽  
Statistical Moment Method

We build the theory of diffusion for FCC binary interstitial alloy under pressure based on the statistical moment method, where there are the analytic expressions of the jumping frequency of interstitial atom, the effective jumping length, the correlation factor, the diffusion coefficient, and the activated energy. In limit cases, we can obtain the diffusion theory for FCC metal A under pressure.

The Effect of Point Defects Interaction on Hydrogen Atom Diffusion in FCC- and BCC-Metals

2008 ◽  
Vol 277 ◽  
pp. 133-138
Author(s):  
Liudmila V. Selezneva ◽  
Andrei V. Nazarov
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Atom ◽  
Potential Barrier ◽  
Point Defects ◽  
Mutual Effect ◽  
Atomic Scale ◽  
Defect Diffusion ◽  
Atom Diffusion ◽  
Complex Defect ◽  
Bcc Metals

This work is devoted to simulation of potential barrier spectrum for hydrogen atom and vacancy jumps in fcc- and bcc- metals taking into account the mutual effect of the point defects on the potential barrier spectrum and as a result the effect on complex defect diffusion in bcc- and fccmetals. The molecular static and the Monte Carlo methods are used. The developed model allows us to determine a diffusion coefficient of the impurity atom depending on temperature and other parameters. The simulation of point defect random walk in lattice on the basis MC-method and potential barrier spectrum has gave an impulse toward an understanding of hydrogen motion on the atomic scale in metals, which is required to determine such important parameters as the diffusion coefficient of H. As well it allows us to understand reasons of more complicated behaviour of H in realistic metal in comparison with perfect metal.

Formation of Point Defects in Dilute FCC Alloys

2008 ◽  
Vol 280-281 ◽  
pp. 79-84 ◽  
Author(s):  
Amitava Ghorai
Keyword(s):  
Point Defects ◽  
Model Potential ◽  
Interstitial Impurity ◽  
Substitutional Impurity ◽  
Fcc Metals ◽  
Atomic Property ◽  
Fcc Alloys ◽  
Pseudopotential Approach ◽  
Formation Energies ◽  
Fcc Metal

Using pseudopotential approach, vacancy formation energy , different non-split interstitial formation energies and binding energy for the vacancy-impurity pair and that for interstitial impurity over host have been calculated in some cubic fcc metal systems, viz. copper, silver, gold and lead using Ashcroft's potential and Taylor's exchange and correlation function with standard (AT) and fitted to (ATF) and also Heine-Abarenkov’s model potential and same exchange and correlations (HAT). It is difficult to have a universal value for all types of atomic property calculations. The results show that ATF and HAT combinations are better in comparison to AT. Also, the substitutional impurity adjacent to a vacancy is found to be more loosely bound than the interstitial impurity in fcc metals.

The Necessary Duration of a Molecular Dynamics Experiment for the Diffusion Coefficient Calculation

2018 ◽  
Vol 30 ◽  
pp. 22-27
Author(s):  
Gennady M. Poletaev ◽  
Ekaterina S. Medvedeva ◽  
Darya V. Novoselova ◽  
Irina V. Zorya ◽  
Mikhail D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Melting Point ◽  
Hydrogen Atom ◽  
Point Defects ◽  
Interstitial Atom ◽  
Mean Square ◽  
Impurity Atoms ◽  
Metal Crystal

The evaluation of the necessary duration of a molecular dynamics experiment for the calculation of the diffusion coefficient at migration of different point defects in Ni (vacancy, bivacancy, self-interstitial atom, hydrogen atom) is held in the present work. It is shown that at the temperature higher than 0.6 of melting point is usually enough the simulation during of 100 ps for this. When calculating of the diffusion coefficient of impurity in the metal crystal, for example, of hydrogen, the decrease of error of mean-square displacements of impurity atoms can be achieved by introducing of a large number of the impurities.

scholarly journals Accuracy of quantum Monte Carlo methods for point defects in solids

2010 ◽  
Vol 248 (2) ◽  
pp. 267-274 ◽  
Author(s):  
William D. Parker ◽  
John W. Wilkins ◽  
Richard G. Hennig
Keyword(s):  
Monte Carlo ◽  
Point Defects ◽  
Monte Carlo Methods ◽  
Quantum Monte Carlo ◽  
Quantum Monte Carlo Methods

Monte Carlo Simulation of Thermophysical Properties for Al-Ce Liquid Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 1404-1407 ◽  
Author(s):  
Wen Jing Yao ◽  
Nan Wang
Keyword(s):  
Monte Carlo ◽  
Diffusion Coefficient ◽  
Thermophysical Properties ◽  
Alloy System ◽  
Simulation Method ◽  
The Monte Carlo Method ◽  
Different Temperatures ◽  
Binary Alloy System ◽  
Eam Potential ◽  
And Diffusion

The Monte Carlo method with EAM potential is applied to simulate the liquid Al-Ce binary alloy system and the thermophysical properties including surface tension (), viscosity () and diffusion coefficient (D) of liquid Al-8at%Ce alloy are determined. The simulated  values decrease with temperature. Based on the relationship between ,  and D, the various viscosity and diffusion coefficient of liquid Al-Ce alloys under different temperatures were determined. The comparison of the simulated results with some experimental measurements is performed and discussed, indicating that the simulation method and EAM parameters in simulation are acceptable. The dependence of viscosity and diffusion coefficient of liquid Al-Ce alloys on temperature is established to be helpful in further investigation of amorphrization ability of Al-Ce alloys.

Joining TiB2-Ni Cermets with Ti6Al4V by Pulse Current Heating

2008 ◽  
Vol 368-372 ◽  
pp. 1609-1611 ◽  
Author(s):  
Yong Peng ◽  
Zheng Yi Fu ◽  
Wei Min Wang ◽  
H. Wang ◽  
Yu Cheng Wang ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Electric Field ◽  
Pulse Current ◽  
Sem Images ◽  
Welding Temperature ◽  
Atom Diffusion ◽  
Different Temperatures ◽  
Cu Foil ◽  
Heating Technology

Pulse current heating technology is used to join TiB2-Ni cermets with Ti6Al4V at different temperatures (1023K, 1073K and 1123K) with 7MPa pressure and Cu foil and Ni foil are used as joining interlayer. Joint points increase with welding temperature. The microstructure of joints is observed through SEM images and micrographs. The diffusion coefficient (D0) of Cu at the Cu/TiB2 interface is calculated by the EPMA patterns. The diffusion principle of pulse current heating and influences of electric field and current on atom diffusion are studied.

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