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Yanilkin A.V.,All Russia Research Institute Of Automatics Named After Nl Dukhov
Physics of the Solid State | Year: 2014

The behavior of hydrogen in zirconium hydride in the high-temperature range has been investigated using the quantum molecular dynamics method. The δ phases of compositions ZrH1.75and ZrH2and the liquid phase are considered. The self-diffusion coefficients of hydrogen are calculated as a function of the temperature in the range from 1000 to 6000 K. For the ZrH1.75and ZrH2hydrides, the obtained values are close to each other. At temperatures of 1000–2000 K, the hydrogen diffusion is determined not only by the mobility of hydrogen atoms but also by the transition from the energetically favorable tetrahedral positions into the excited state. The obtained values of the diffusion coefficients in the temperature range of 1000–1200 K are in good agreement with the experimental data. © 2014, Pleiades Publishing, Ltd. Source


Malygin G.A.,RAS Ioffe Physical - Technical Institute | Ogarkov S.L.,All Russia Research Institute Of Automatics Named After Nl Dukhov | Andriyash A.V.,All Russia Research Institute Of Automatics Named After Nl Dukhov
Physics of the Solid State | Year: 2013

The plastic deformation of metallic crystals under intense shock wave loading has been theoretically investigated. It has been experimentally found that the plastic strain rate e{open} and the pressure in the wave P are related by the empirical expression e{open} ~ P4 (the Swegle-Grady law). The performed dislocation-kinetic analysis of the mechanism of the origin of this relationship has revealed that its power-law character is determined by the power-law pressure dependence of the density of geometrically necessary dislocations generated at the shock wave front ρ ~ P3. In combination with the rate of viscous motion of dislocations, which varies linearly with pressure (u ~ P), this leads to the experimentally observed relationship e{open} ~ P4 for a wide variety of materials with different types of crystal lattices in accordance with the Orowan relationship for the plastic strain rate e{open} = bρu (where b is the Burgers vector). In the framework of the unified dislocation-kinetic approach, it has been theoretically demonstrated that the dependence of the pressure (flow stress) on the plastic strain rate over a wide range from 10-4 to 1010 s-1 reflects three successively developing processes: the thermally activated motion of dislocations, the viscous drag of dislocations, and the generation of geometrically necessary dislocations at the shock wave front. © 2013 Pleiades Publishing, Ltd. Source


Malygin G.A.,RAS Ioffe Physical - Technical Institute | Ogarkov S.L.,All Russia Research Institute Of Automatics Named After Nl Dukhov | Andriyash A.V.,All Russia Research Institute Of Automatics Named After Nl Dukhov
Physics of the Solid State | Year: 2013

Analytical expressions for the front of a shock plastic wave and the plastic relaxation region behind the front have been obtained and a relation of the wave parameters to the pressure in the wave has been determined in the framework of the dislocation kinetic approach based on kinetic relationships and equations for the density of dislocations. Within this approach, the physical mechanism of the origin and the universality of the Swegle-Grady empirical relationship for crystals in the form of a power-law dependence of the plastic strain rate e{open} on the pressure in the wave P, that is, e{open} ~ P4, have been discussed. The principal contribution to this dependence comes from the power-law (cubic) dependence of the density of dislocations generated in the wave front on the pressure. The universality of the Swegle-Grady relationship is based on the invariance of the dissipative action A. An explicit expression for the dissipative action has been derived: A = SBV0/3β. As follows from this expression, the dissipative action is determined by fundamental parameters for shock wave loading of crystals, such as the dislocation viscous drag coefficient B and the adiabaticity factor S (here, V0 is the specific volume and β is a coefficient of the order of 10-3-10-2). In light of the revealed circumstances, such phenomenological notions as the Hugoniot elastic limit and the elastic precursor have been critically examined. © 2013 Pleiades Publishing, Ltd. Source


Brazhnikov P.P.,All Russia Research Institute Of Automatics Named After Nl Dukhov | Andrianov V.P.,All Russia Research Institute Of Automatics Named After Nl Dukhov | Koltovoy O.N.,All Russia Research Institute Of Automatics Named After Nl Dukhov | Tikhov A.A.,All Russia Research Institute Of Automatics Named After Nl Dukhov
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Interferometric system for detecting radiation wavelength shift functions based on a Fabry-Perot interferometer. Means developed for enhancing the system performance are described, namely: a method of increasing illumination of detected fringes for enhancing the system sensitivity, and a method of compensating interference maxima spreading caused by nonparallelism of mirrors that allows enhancing accuracy of light frequency shift measurement. The way to increase detected fringe brightness is based on additional reduction of the divergence of passing through the interferometer light beam. This method allows compensating negative effect of collimating lens spherical aberrations, and, using them, increasing the detector illumination. The way of compensating the interferometer mirrors nonparallelism effect on the detected fringe is based on use of specific relative position of beams from various parts of the interferometer near the focal plane of the focusing lens. © 2014 SPIE. Source

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