K. P. Zol’nikov

Possibility of a vortex mechanism of displacement of the grain boundaries under high-rate shear loading

The behavior of the boundaries of grains of special type in the material during high-rate shear loading was studied numerically. Two paths of evolution of the simulated system were shown: an intense rearrangement of the intergrain boundary occurs at high deformation rates and the process of relaxation of the energy supplied to the material is accomplished by displacing the boundary as the intensity of loading is decreased. The calculations showed that the intergrain boundary can be shifted with an abnormally fast speed. Vortex collective motion of the atoms causes high velocities of displacement of the grain boundaries.

Anisotropy of the plastic deformation and fracture processes in a dynamically loaded crystallite

The influence of anisotropic dynamic loading on the character of plastic deformation and fracture processes in a crystallite near the free surface was studied by methods of molecular dynamics. It was established that there are threshold deformation levels determining the opening of a seeding crack (notch) and the subsequent crack stop. The simulation results show that loading in the [100] direction leads to the crack stop due to the formation of a disordered material region at the crack tip.

Nonlinear effects in dynamic loading of a material with defect zones

An analysis is made of some characteristic features of the interaction between solitary pulses (soliton-like waves) generated under high-velocity loading and structural defects in an Al crystallite. Calculations are made using the molecular dynamics method. It is shown that in materials undergoing shear loading and those undergoing compression different types of solitary pulses are formed which interact differently with regions containing structural defects. The waves formed under compression have a higher propagation velocity in the material, and their profile recovers fairly rapidly after propagating through defect zones. These phenomena are of interest for developing methods of nondestructive testing.

Atomic mechanisms of local structural rearrangements in strained crystalline titanium grain

The nucleation and development of plastic deformation in a crystalline grain of titanium (Ti) during uniaxial tension has been studied by molecular dynamics (MD) simulations with the interatomic interaction described using the embedded atom method. Specific features of the generation of local structural rearrangements in the grain at various straining rates are revealed. It is established that there is a threshold deformation level at which local structural rearrangements begin to nucleate in the crystal, which is accompanied by a jumplike decrease in the potential energy. Because of the inertial character of the accommodation processes, this threshold value increases with the loading velocity.

The possibility of forming soliton-like pulses during ion implantation

The nonlinear response of a material under a high-energy process acting on groups of atoms or individual atoms of a free surface is studied. The dissipation of the energy transferred by soliton-like pulses at structural defects, such as regions with high vacancy density, grain boundaries, and the free surface, is investigated. A method of describing the “longrange action” during ion implantation in metallic materials is proposed.

Possible nonlinear heat-pulse propagation in solids at Debye temperatures

Molecular dynamics techniques are used to show that heat can be transferred ballistically in threedimensional crystalline materials at temperatures on the order of Debye temperatures.

Effect of the anisotropy of confining field on the structure of dusty plasma clusters

The structure of dusty plasma clusters in the ground state for various configurations of the confining field has been simulated using the molecular dynamics method with the interaction between spherical particles of dusty plasma described in terms of an isotropic Yukawa pair potential. Depending on the degree of the confining field anisotropy (i.e., a difference between forces in the vertical and horizontal directions), conditions for which a three-dimensional (3D) structure in the ground state (isotropic confining field) transforms into a 2D structure are determined. The shape, dimensions, and structure of dusty plasma clusters have been studied in systems with various numbers of particles and degrees of anisotropy of the confining field.

Size effect on the kinematic parameters of nanometer-thick bilayer films

The behavior of nanodimensional bilayer structures (plates) of finite length consisting of nanometer-thick crystalline Ni and Cu films has been studied by means of molecular dynamics simulation. The inter-atomic interactions were described within the framework of the embedded atom method. It is shown that, in the absence of an external action, the nanostructures perform mechanical oscillations with the amplitude and frequency determined by the length and thickness of the plate. The dependence of the parameters of oscillations of the nanodimensional structures on their dimensions is established. The results can be used in designing components of nanodevices for various applications.

Structural features of two-component dusty plasma Coulomb balls

A binary mixture of dust particles in plasma occurring in an external electrostatic spherical confinement field has been numerically simulated. Calculations have been performed within the framework of the molecular dynamics method, with the interparticle forces described in terms of an isotropic Yukawa pair potential. It is shown that the particles form a shell structure, each particular shell consisting of particles of the same kind. The structural properties of such a binary mixture of particles and the specific features of their segregation under the conditions of recent experiments on the formation of Coulomb balls have been studied.

New approach to the application of multilayer superthin coatings. Effects of mixing

It is shown within the framework of molecular-dynamic modeling that the interaction of a nonlinear pulse with a free surface can result in the separation of an atomic plane. According to the results obtained upon colliding with the target, the separated fragments can form a multilayer coating. This has formed the basis of the proposed approach to the level-by-level application of thin coatings. It is shown that the change in the number of pulses and in the time for which they reach the surface of a “source” can significantly change the structure and composition of the coating at the target.