scholarly journals Влияние примесей легких элементов на скорость движения фронта кристаллизации в Ni и Ag: молекулярно-динамическое моделирование

2020 ◽  
Vol 46 (12) ◽  
pp. 6
Author(s):  
Г.М. Полетаев ◽  
И.В. Зоря
Keyword(s):  
Molecular Dynamics ◽  
Crystallization Front ◽  
Crystallization Rate ◽  
Local Deformation ◽  
Light Elements ◽  
Fcc Metals ◽  
Impurity Atoms ◽  
Method Of Molecular Dynamics ◽  
Effect Of Impurities ◽  
Concentration Of Impurities

The effect of impurities of light elements C, N, O on the velocity of motion of the crystallization front in fcc metals Ni and Ag was studied by the method of molecular dynamics. The dependences of the crystallization rate on the concentration of impurities are obtained. It is shown that the presence of impurities leads to a significant slowdown in the velocity of motion of the crystallization front in metals. Braking of the crystallization front by the impurity atoms is associated with the local deformation of the crystal lattice that they cause, and, as a rule, the greater this deformation, the stronger the impurity atoms inhibit the crystallization front.

scholarly journals Effect of light elements impurity on process of nickel crystallization near the triple interface of grain boundaries: a molecular dynamics simulation

2020 ◽  
Vol 63 (5) ◽  
pp. 357-363
Author(s):  
I. V. Zorya ◽  
G. M. Poletaev ◽  
M. D. Starostenkov ◽  
R. Yu. Rakitin ◽  
D. V. Kokhanenko
Keyword(s):  
Molecular Dynamics ◽  
Boundary Conditions ◽  
Crystal Lattice ◽  
Grain Boundaries ◽  
Melting Temperature ◽  
Crystallization Front ◽  
Light Elements ◽  
Cylinder Axis ◽  
Impurity Atoms ◽  
Effect Of Impurities

Molecular dynamics method was used to study the effect of impurities of light elements of carbon, nitrogen and oxygen on crystallization process near the triple interface of grain boundaries in nickel. Tilt boundaries with misorientation axis <111> were considered as the grain boundaries. Interactions of nickel atoms with each other were described by many-particle Clery-Rosato potential constructed within the framework of the tight binding model. To describe interactions of atoms of light elements impurities with nickel atoms and atoms of impurities with each other, Morse pair potentials were used. Calculation cell had a shape of cylinder, axis of which coincided with the line of triple interface and the axis of grain misorientation. Periodic boundary conditions were imposed along the cylinder axis, and the atoms on side surface of cylinder were motionless. To simulate crystallization, calculation cell was melted by heating to a temperature well above the melting temperature of nickel. After the simulated polycrystal become liquid, the thermostat was turned on and held at a constant temperature below the melting temperature. Rigid boundary conditions on the lateral surface of cylindrical calculation cell in this case simulated crystallization fronts from three crystallization centers. The area near the triple interface had crystallized the last. In this area, defects and free volume were concentrated. Presence of impurities led to a significant slowdown in the rate of crystallization. With introduction of 10 % of impurity atoms, the rate of motion of crystallization front decreased several times. The effect of impurities on crystallization rate was enhanced in C – N – O direction, which is due to difference in crystal lattice deformation caused by impurity atoms. The greater this deformation was, the stronger was impurity atoms inhibit crystallization front. Formation of aggregates at fairly high concentrations was typical for impurity carbon atoms. Crystallization front had impeded on these aggregates. The oxygen and nitrogen atoms did not form aggregates. However, due to distortions of crystal lattice caused by them, they also strongly slowed down the crystallization front.

The Causes of Formation of the Triple Junctions of Grain Boundaries Containing Excess Free Volume in fcc Metals at Crystallization

2016 ◽  
Vol 247 ◽  
pp. 3-8 ◽  
Author(s):  
Gennady M. Poletaev ◽  
Darya V. Novoselova ◽  
Valentina M. Kaygorodova
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Free Volume ◽  
Crystallization Process ◽  
Triple Junctions ◽  
Phase Density ◽  
Fcc Metals ◽  
Excess Free Volume ◽  
Method Of Molecular Dynamics ◽  
Formation Conditions

The formation conditions of strained (non-equilibrium) triple junctions of grain boundaries were studied by the method of molecular dynamics. It is shown that strained triple junctions, containing excess free volume, mainly forms during crystallization process in the result of "locking" of the liquid phase density at a meeting of the three crystallization fronts and, as a consequence, of the concentration of excess free volume in the triple junction after solidification.

scholarly journals Effect of light elements impurity atoms on grain boundary diffusion in FCC metals: a molecular dynamics simulation

2020 ◽  
Vol 62 (12) ◽  
pp. 930-935
Author(s):  
G. M. Poletaev ◽  
I. V. Zorya ◽  
R. Yu. Rakitin ◽  
M. D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Crystal Lattice ◽  
Grain Boundaries ◽  
Free Volume ◽  
Misorientation Angle ◽  
Light Elements ◽  
Self Diffusion ◽  
Impurity Atoms ◽  
Metal Atoms

Effect of carbon and oxygen impurity atoms on diffusion along the tilt grain boundaries with <100> and <111> misorientation axis in metals with FCC lattice was studied by mean of molecular dynamics method. Ni, Ag, and Al were considered as metals. Interactions of metal atoms with each other were described by many-particle Clery-Rosato potentials constructed within the framework of tight binding model. To describe interactions of atoms of light elements impurities with metal atoms and atoms of impurities with each other, Morse pair potentials were used. According to obtained results, impurities in most cases lead to an increase in self-diffusion coefficient along the grain boundaries, which is caused by deformation of crystal lattice near the impurity atoms. Therefore, additional distortions and free volume are formed along the boundaries. It is more expressed for carbon impurities. Moreover, with an increase in concentration of carbon in the metal, an increase in coefficient of grain-boundary self-diffusion was observed first, and then a decrease followed. This behavior is explained by formation of aggregates of carbon atoms at grain boundary, which leads to partial blocking of the boundary. Oxygen atoms had smaller effect on diffusion along the grain boundaries, which is apparently explained by absence of a tendency to form aggregates and lesser deformation of crystal lattice around impurity. The greatest effect of impurities on self-diffusion along the grain boundaries among the examined metals was observed for nickel. Nickel has the smallest lattice parameter, impurity atoms deform its lattice around itself more than aluminum and silver, and therefore they create relatively more lattice distortions in it and additional free volume along the grain boundaries, which lead to an increase in diffusion permeability. Diffusion coefficients along the high-angle boundaries with misorientation angle of 30° turned out to be approximately two times higher than along low-angle boundaries with a misorientation angle of 7°. Diffusion along the <100> grain boundaries flowed more intensively than along the <111> boundaries.

scholarly journals Interaction of impurity atoms of light elements with self-interstitials in fcc metals

2019 ◽  
Vol 9 (2) ◽  
pp. 207-211 ◽  
Author(s):  
Irina Zorya ◽  
Gennady Poletaev ◽  
Roman Rakitin ◽  
Marina Ilyina ◽  
Mikhail Starostenkov
Keyword(s):  
Light Elements ◽  
Fcc Metals ◽  
Impurity Atoms

A Study on the Uniaxial Tension of FCC Metals at Nano Level Using MD

2008 ◽  
Vol 32 ◽  
pp. 255-258
Author(s):  
Bohayra Mortazavi ◽  
Akbar Afaghi Khatibi
Keyword(s):  
Molecular Dynamics ◽  
Uniaxial Tension ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Engineering Strain ◽  
Fcc Metals ◽  
Engineering Stress ◽  
Nano Science ◽  
Face Centered

Molecular Dynamics (MD) are now having orthodox means for simulation of matter in nano-scale. It can be regarded as an accurate alternative for experimental work in nano-science. In this paper, Molecular Dynamics simulation of uniaxial tension of some face centered cubic (FCC) metals (namely Au, Ag, Cu and Ni) at nano-level have been carried out. Sutton-Chen potential functions and velocity Verlet formulation of Noise-Hoover dynamic as well as periodic boundary conditions were applied. MD simulations at different loading rates and temperatures were conducted, and it was concluded that by increasing the temperature, maximum engineering stress decreases while engineering strain at failure is increasing. On the other hand, by increasing the loading rate both maximum engineering stress and strain at failure are increasing.

Molecular Dynamics Simulations of High Energy Cascades in Iron

1994 ◽  
Vol 373 ◽  
Author(s):  
Roger E. Stoller
Keyword(s):  
Molecular Dynamics ◽  
Three Dimensional ◽  
High Energy ◽  
Dynamics Simulation ◽  
Method Of Molecular Dynamics ◽  
Energy Cascades ◽  
Iron Based ◽  
The Many ◽  
Property Changes ◽  
Dynamics Simulations

AbstractA series of high-energy, up to 20 keV, displacement cascades in iron have been investigated for times up to 200 ps at 100 K using the method of molecular dynamics simulation. Thesimulations were carried out using the MOLDY code and a modified version of the many-bodyinteratomic potential developed by Finnis and Sinclair. The paper focuses on those results obtained at the highest energies, 10 and 20 keV. The results indicate that the fraction of the Frenkel pairs surviving in-cascade recombination remains fairly high in iron and that the fraction of the surviving point defects that cluster is lower than in materials such as copper. In particular, vacancy clustering appears to be inhibited in iron. Some of the interstitial clusters were observed to exhibit an unexpectedly complex, three-dimensional morphology. The observations are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

scholarly journals SPECTRAL FEATURES AND HYDROGEN BOND STRUCTURE OF AQUEOUS SOLUTIONS OF ETHANOL

2021 ◽  
pp. 30-33
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Gaseous Medium ◽  
Water Molecules ◽  
Structural Reorganization ◽  
Intermolecular Hydrogen Bonds ◽  
Method Of Molecular Dynamics ◽  
Combined Use ◽  
Structure Of Aqueous Solutions

The aim of this work is develop an approach that makes it possible to study the spectral properties and structure of intermolecular hydrogen bonds in aqueous solutions of ethanol formed in systems whose existence in a gaseous medium or an isolated state is practically impossible. This approach bases on the combined use of infrared spectroscopy and molecular dynamics (MD) methods. An analysis give the structural reorganization of water molecules depending on the concentration of ethanol alcohol. It has been shown that the method of molecular dynamics with classical force fields makes it possible to explicitly take into account the molecules of the solvent and solute, and, thus, to investigate hydrogen bonds in the system and to interpret with the experimental data obtained by vibrational spectroscopy.

Sign in / Sign up

Export Citation Format

Share Document