scholarly journals Влияние концентрации вакансий на скорость миграции границ наклона в никеле: молекулярно-динамическое моделирование

2021 ◽  
Vol 47 (8) ◽  
pp. 29
Author(s):  
Г.М. Полетаев ◽  
Р.Ю. Ракитин
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Migration Rate ◽  
Vacancy Concentration ◽  
High Angle ◽  
Vacancy Clusters ◽  
Method Of Molecular Dynamics ◽  
Initial Stage ◽  
Tilt Boundaries ◽  
Small Clusters

The effect of vacancy concentration on the migration rate of high-angle tilt boundaries with misorientation axes <111> and <100> in nickel was studied by the method of molecular dynamics. It is shown that the dependence of the migration rate of grain boundaries on the vacancy concentration is nonmonotonic and has a maximum at a concentration of vacancies introduced at the initial stage of about 1%. With a further increase in concentration, especially above 4%, the migration rate of the considered boundaries decreased as a result of deceleration of boundaries by low-mobility vacancy clusters attached to it, which the boundary could no longer sorb, as in the case of relatively small clusters.

scholarly journals Молекулярно-динамическое исследование влияния концентрации вакансий на скорость миграции границ наклона в никеле

2021 ◽  
Vol 63 (5) ◽  
pp. 582
Author(s):  
Г.М. Полетаев ◽  
Р.Ю. Ракитин
Keyword(s):  
Free Volume ◽  
Driving Force ◽  
Migration Rate ◽  
Vacancy Concentration ◽  
High Angle ◽  
Vacancy Clusters ◽  
Method Of Molecular Dynamics ◽  
Initial Stage ◽  
Tilt Boundaries ◽  
Mobile Vacancy

The influence of vacancy concentration on the migration rate of high-angle tilt boundaries with misorientation axes <111> and <100> in nickel was studied by the method of molecular dynamics. It is shown that the dependence of the migration rate on the concentration of vacancies introduced at the initial stage of modeling has a maximum near 1%. The decrease in the migration rate with a further increase in the free volume is mainly due to the deceleration of the boundary by low-mobile vacancy clusters, which at high vacancy concentrations the boundary is no longer capable of sorbing. The second reason for the decrease in the migration rate with an increase in the concentration of vacancies above 1% is a decrease in the surface tension of grain boundaries and, accordingly, the driving force of their migration due to the finite sorption capacity of the boundaries with respect to the excess free volume.

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.

Lattice Thermal Conductivity of Fe-Cr Alloys With 〈001〉 Tilt Boundaries: An Atomistic Study

2014 ◽  
Author(s):  
Ishraq Shabib ◽  
Mohammad Abu-Shams ◽  
Mujibur R. Khan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Lattice Thermal Conductivity ◽  
The Other ◽  
Tilt Boundaries ◽  
Cr Concentration ◽  
Non Equilibrium Molecular Dynamics ◽  
Atomistic Study

The objective of this study is to examine lattice thermal conductivity (κ) of Fe-Cr alloys containing different 〈001〉 tilt grain boundaries (GBs). The effects of Cr concentration (2 and 10%) and three different 〈001〉 tilt boundaries (Σ5{310}, Σ13{510}, and Σ17{530}) have been examined at 70K using the reverse non-equilibrium molecular dynamics (rNEMD) simulation technique. The results exhibit higher κ for Fe or Fe-Cr models with Σ5[310] GB. The values are 2–4% and 12–16% more than those of models with Σ13[510] and Σ17[530] GBs, respectively. Pure Fe single crystal models exhibit higher conductivities than Fe/Fe-Cr models with various Σ tilt boundaries. κ decreases 7–9% as GBs are introduced into the pure Fe single crystal models. On the other hand, the conductivities of Fe-Cr models are affected more by the Cr concentration than the presence of a particular GB. As 10% Cr is added into the system the conductivity decreases by 7.6–9.4% compared to the pure Fe models.

Simulation of Recrystallization Using Molecular Dynamics; Effects of the Interatomic Potential

2007 ◽  
Vol 558-559 ◽  
pp. 1081-1086 ◽  
Author(s):  
Rasmus B. Godiksen ◽  
Zachary T. Trautt ◽  
Moneesh Upmanyu ◽  
Søren Schmidt ◽  
Dorte Juul Jensen
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Interatomic Potential ◽  
Driving Forces ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
High Angle ◽  
Embedded Atom ◽  
Atomic Interactions

Recrystallization is governed by the migration of high angle grain boundaries traveling through a deformed material driven by the excess energy located primarily in dislocation structures. A method for investigating the interaction between a migrating grain boundary and dislocation boundaries using molecular dynamics (MD) was recently developed. During simulations migrating high angle grain boundaries interact with dislocation boundaries, and individual dislocations from the dislocation boundaries are absorbed into the grain boundaries. Results obtained previously, using a simple Lennard-Jones (LJ) potential, showed surprisingly irregular grain boundary migration compared to simulations of grain boundary migration applying other types of driving forces. Inhomogeneous boundary-dislocation interactions were also observed in which the grain boundaries locally acquired significant cusps during dislocation absorption events. The study presented here makes comparisons between simulations performed using a LJ- and an embedded atom method (EAM) aluminum potential. The results show similarities which indicate that it is the crystallographic features rather than the atomic interactions that determine the details of the migration process.

scholarly journals MOLECULAR-DYNAMICS RESEARCH OF STRUCTURE OF TRIPLE JUNCTIONS OF TILT BOUNDARIES AND MIXED-TYPE GRAIN BOUNDARIES IN NICKEL

2015 ◽  
Vol 56 (4) ◽  
pp. 46
Author(s):  
G. M. Poletaev ◽  
D. V. Dmitrienko ◽  
V. V. Diabdenkov ◽  
V. R. Mikrukov ◽  
M. D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Mixed Type ◽  
Triple Junctions ◽  
Tilt Boundaries

Structure of high-angle-tilt boundaries in YBa2Cu3-O7-x thin films

1991 ◽  
Vol 49 ◽  
pp. 1086-1087
Author(s):  
D. H. Shin ◽  
J. Silcox ◽  
S. E. Russek ◽  
D. K. Lathrop ◽  
B. H. Moeckly ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Weak Link ◽  
Boundary Region ◽  
Atomic Scale ◽  
High Resolution Imaging ◽  
High Angle ◽  
Superconducting Properties ◽  
Tilt Boundaries ◽  
Resolution Imaging

It has been known that high angle tilt grain boundaries in c-axis oriented YBa2Cu3O7-x thin films cause weak link behavior in the transport properties reducing Jc's by several orders of magnitude. These grain boundaries have been shown to be clean both structurally and chemically by high resolution imaging and microanalysis studies. Therefore the mechanism of weak link behavior in thin film YBa2Cu3O7-x is not yet understood.Recently it has been deduced from the behavior of weak link Jc under small magnetic fields that the high angle tilt boundaries are nonuniform, consisting of several regions of good contact, each about 5-10 % of the boundary length, with the rest of the boundary region being poor. This seems to suggest that the superconducting properties at the boundary may be sensitive to changes in structures of atomic scale, since typical grain boundaries are free of macroscopic (≥ 10 Å) defects all along the boundaries.

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