[en] We consider a weak supersaturated binary solid solution under continuous irradiation. Irradiation produces collision cascades in the media. Local energy deposition within a cascade zone, as is known, causes relaxation of the excess temperature to an ambient level. A simple model, that is taking into account the effect of temperature relaxation to a clustering formation of alloying atoms, is presented. The model is based on general principles of irreversible non-equilibrium thermodynamics. It is shown that the relaxation and thermodiffusion processes in supersaturated alloys may result in spatial redistribution of solute atoms in the media

[en] The homogeneous distribution of voids in irradiated metals is unstable due to spatially inhomogeneous fluctuations. Void ordering by the incident flow to voids of radiation-induced vacancies and by the backward flow is studied theoretically. The latter flow can be provided with absorption of point defects by vacancy dislocation loops and/or with the emission of vacancies from voids

[en] The theory of interstitial loop nucleation and growth in metals at the beginning of irradiation is developed. After some transient time the loop concentration becomes constant and both interstitial and vacancy diffusion fluxes achieve their steady state values. At this stage vacancy cluster nucleation becomes possible. Analytical expressions for the loop concentration, the characteristic times of their growth and the start for vacancy clustering are obtained. It is shown that for given irradiation conditions some critical density of dislocation network exists. For higher densities the process of loop formation under irradiation is suppressed due to interstitial absorption in sinks. (author)

[en] The physical mechanism of the spatially homogeneous void ensemble state instability with respect to small void size deviations induced by vacancy emission from voids is demonstrated by means of both the exact diffusion and chemical rate equations for the point defect concentrations in a volume containing voids. As it was shown in previous papers the corresponding instability conditions can be valid at rather high irradiation temperatures (higher than the swelling maximum). Here the nonlinear analysis of the void system response to small void size variations is carried out to obtain the qualitative characteristics of spatially ordered void distribution when the instability concerned takes place. Void ordering is the result of the spatially homogeneous void shrinkage after the completion of void nucleation process. Only 'ordered' voids survive. The mathematical investigation is based on the conception of slowly and rapidly varying distributions, which is used to describe in unified fashion a spontaneous formation of ordered structures in a large class of nonequilibrium physical systems, whose properties depend on the parameters that differ in their spatial dispersion. In the case under consideration the spatial diffusion lengths of point defects and voids are such parameters. It is shown that the constructed periodical void distribution is stable in time with respect to small void size deviations. The roles of the anisotropic transport of self-interstitials in the void spatial ordering and the stochastic fluctuations of void growth rate in the expansion of the temperature range of the nonequilibrium phase transition from a spatially disordered to an ordered void system state are also discussed. (orig.)

[en] The motion of point defects in a solution is of a stochastic nature. Therefore their number in any finite volume fluctuates. The void growth rate undergoes stochastic fluctuations. The amplitude of these fluctuations depends on the sum of vacancy and interstitial fluxes to the void. A spatially random void distribution results in small spatial variations of the swelling rate from void to void. The condition for the stochastic fluctuations of point defect concentrations to increase crucially the amplitude of the small variations concerned is obtained on the basis of the stochastic description of the void evolution under irradiation. The instability of the spatially homogeneous void distribution arises due to the essential difference of the parameters characterizing the systems of voids and point defects. It is also shown that voids of sizes typical for void lattices in Mo can become spatially ordered by means of a Brownian-like motion after a dose of about 10 dpa. (orig.)

[en] The void system being formed under irradiation is an open dissipative system. When the point defect production rate is lower than the critical one found and the dislocation density is comparatively small, inhomogeneous fluctuations of the point defect concentrations can lead to an instability of the homogeneous (random) void distribution and therefore to a spatial reorganization of voids under irradiation. (author)

[en] The nature of point defect production in collision cascades due to heavy ion and neutron irradiation causes fluctuations of vacancy and interstitial concentrations. These fluctuations are shown to affect the void growth kinetics in irradiated metals. In the present paper the analysis of the void distribution behaviour as a function of void size is considered. Remarkable changes in void kinetics can exist when the dislocation density is comparatively small. Under conditions determined in the present paper, the cascade induced fluctuations of the void growth rate lead to some decrease in the void density in irradiated metals. Moreover, spatially inhomogeneous void shrinkage prevails over the homogeneous shrinkage. (Author)

[en] The orientational dependence of the elastic scattering of fast nonrelativistic electrons in monocrystals has been investigated when the energy of transverse motion (E/sub perpendicular to/ = E theta₀²) is smaller than the energy of the ''bound'' state of the atomic plane. The presence of the ''bound'' state of transverse motion in the effective attractive potential of the crystallographic planes leads to the radiation gamma-quantum when the electron transits into the discrete spectrum state. This effect is responsible for the production of the orientational maxima in the bremsstrahlung spectrum of nonrelativistic electrons. (U.S.)

[en] The elastic scattering of a fast particle in an atom at high energy is treated as diffraction, wherein there appears a diffraction shadow whose blackness depends on the particle interaction with the atom. Calculations are presented to account for the shadowing effect in crystals. (U.S.)

[en] A physical model of carbon stripper foil failure is presented. Failure of foils as a result of radiation induced stresses exceeding the ultimate strength is considered. These stresses are ascribed to lattice distortion caused by point defect accumulation inferred from kinetic rate equations with defect sinks being considered. The linear changes account for the lattice anisotropy. The advantage of this model as compared with others is that it uses no fitting parameters. On the basis of the model, the experimental data of carbon stripper foil lifetimes in ion beams are analysed. The calculated foil lifetimes agree well with the experimental data. (orig.)