Papers by Author: Mikhail D. Starostenkov

Abstract: The energy characteristics of interaction of hydrogen impurity with ½<110> edge dislocation in Pd and Ni were calculated by the method of molecular dynamics. It is shown that the dislocation is effective trap for hydrogen. At the same time the dislocation jogs increases its sorption capacity with respect to hydrogen, but reduces the diffusion mobility of hydrogen along the dislocation. The diffusion of hydrogen atoms in the dislocation region occurs mainly along the dislocation core. The energy of hydrogen migration along the dislocation, as our calculations have shown, is almost two times lower than in a defect-free crystal.

Abstract: In this work, the authors attempted to consider the influence of the geometry of the crystal lattice on the properties of nanowires, which manifest themselves in the process of uni-axial stretching. This work summarizes and systematizes the results of previous studies of the authors. The first group of samples – are typical FCC metal – Ni₃Al. For these nanowires, deformation processes in directions with different packing densities of atoms <100>, <110> and <111> were investigated. The second material group studied was an alloy with the non-cubic symmetry of the element cell CuAu I. Correspondingly, this sample was examined under deformation in directions corresponding to different lengths of the sides of the unit cell, <001> and <010>. All the investigations described in this paper were carried out by molecular dynamics method on three-dimensional models using the Morse's pair potentials.

Abstract: 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.

Abstract: In the work we propose a method for determining of the formation energy of bivacancy using molecular dynamics method. The key moment of the method for determining of the formation energy of bivacancy is the use of the value ζ, the minimum work that must be spent to remove one atom to infinity from the kink in the monatomic step on the surface of the crystal, calculated indirectly through the experimental data on the formation energy of the vacancy and the sublimation energy. The energy of migration of bivacancy in the work was determined from the temperature dependence of the diffusion coefficient when one bivacancy was introduced into the calculation block.

Abstract: The research of quasi-breather statistical characteristics in the model crystal of A₃B stoichiometry is conducted by means of molecular dynamics method in the paper by the example of Pt₃Al. The phonon spectrum of this model crystal, the dependences of mean-square deviation, the coefficient of variation and the average frequency of the model quasi-breather on the time of its existence are obtained. The statistical data analysis allows for the conclusion that a quasi-breather model solution slightly differs from the exact breather corresponding to it in the model under consideration using the interatomic potential obtained by means of embedded atom method (EAM).

Abstract: Using the method of molecular dynamics, FCC Ni nanowires containing hydrogen atoms in octahedral and tetrahedral pores are investigated in the course of high-speed uniaxial tensile loading along the direction <001>. The feature of structural transformations in Ni nanowires containing hydrogen is appearance on the stage of plastic deformation globular (spherical) formations consisting of hydrogen atoms

Abstract: A many-body interatomic potential for metallic nanowires within the second-moment approximation of the tight-binding model (the Cleri-Rosato potential) was employed to carry out three dimensional molecular dynamics simulations. Molecular dynamics simulation results for metallic nanowires at various temperature are presented. The stress–time and stress length curves for nanowires are simulated. The breaking and yield stress of nanowires are dependent on the Volume and temperature. The necking, Plastic deformation, slipping domain, twins, clusters, microspores and break-up phenomena of nanowire are demonstrated. Stress decreases with increasing nanowire volume and temperature. The final breaking position occurs at the central part of the nanowire when it is short, as the nanowire length increases the breaking position gradually shifts to the ends.

Abstract: By method of molecular dynamics discrete breathers with soft and hard types of non-linearity in the Pt₃Al crystal are studied. Obtained graphs characterize the spatial localization of the discrete breathers, the dependence of the frequency on the oscillation amplitude and the amount of energy localized on the discrete breathers. It is shown that the collision of moving discrete breathers may lead to the energy exchange between the breathers with some portion of the energy given to the Pt₃Al lattice. The probability of excitation of discrete breathers in thermodynamic equilibrium is estimated.

Abstract: The interaction of atom-atom collisions cascades with Ni-Al interphase boundary was studied by the method of molecular dynamics. It was shown that the interphase boundary partially absorbs the cascade energy. The degree of energy absorption of the cascade by the interphase boundary increases with the growth of the structural imperfection of the boundary and density of the misfit dislocations, and also with increase of distance between the boundary and the place of the cascade initiation.

Abstract: Molecular Dynamics (MD) simulations have been carried out on ultrathin Ni₃Fe alloy with face-centered cubic (FCC) lattice upon application of uniaxial tension at nanolevel with a speed of 20 m/s. the deformation corresponds to the direction <001>. To the calculated block of crystal - free boundary conditions are applied in the directions <100>, <010>. Morse potential was employed to carry out three dimensional molecular dynamics simulations. A computer experiment is performed at a temperature corresponding to 300 K. MD simulation used to investigate the effect of long of ultrathin Ni₃Fe alloy on the nature of deformation and fracture. The engineering stress–time diagrams obtained by the MD simulations of the tensile specimens of these ultrathin Ni₃Fe alloy show a rapid increase in stress up to a maximum followed by a gradual drop to zero when the specimen fails by ductile fracture. The feature of deformation energy can be divided into four regions: quasi-elastic, plastic, flow and failure. The yield strength decreased with increasing long of alloy, but increases with increasing the cross sectional area. Plasticity disappear when the length of the allays is too large. The results showed that breaking position depended on the alloy length.