Search

Addition of titanium increases the strength and plasticity of Al-Zn-Mg system casting alloys. The alloys with 0.2–0.3% Ti have the best mechanical properties. These alloys strengthen during natural and artificial aging without preliminary hardening. The highest strength is reached after hardening and artificial aging. Fracture of the alloys after heat treatment has a ductile character. Local deformation occurs nonuniformly in the alloys. The alloys are not prone toward general or intergranular corrosion.

The principal stages of oceanographic investigation by the Soviet Union's series of North Pole drift-ice stations are reviewed. It is shown how the findings of these floating research stations, beginning with North Pole-1 in 1937, gave rise to modern views on the character of bottom topography, water masses, water and ice circulation and marine life in the Arctic Basin. The main results of the studies are described.

A metallic single crystal is considered as a thermodynamic system interacting with a surrounding medium by mechanical and thermal forms of motion in an irreversible process. The equations determining the process are obtained, taking account of the changes in structure and thermal conductivity of the crystal, for which new concepts of mathematical expectation and additional stress are introduced.

The evaporation of drops of mixtures of tetrafluorodibromethane with benzene, toluene, and xylene is studied at room temperature in air at rest.

Conclusions 1.We observed a qualitative agreement between results obtained by extending a simplified variant of the kinetic strain theory to the class of generalized functions on the one hand and data from [3] on viscoelastic media based on completely different premises on the other hand.2.By replacing the first-order time derivatives by fractional derivatives in the governing equations of any variant of viscoelasticity or viscoplasticity, it is possible to obtain Volterra-type integral equations with kernels retaining a singularity of type found in an Abel kernel for the purpose of describing the initial stage of relaxation and creep of materials.

Conclusions 1.The set of characteristic Eqs. (1), obtained on the basis of separating stresses into equilibrium and nonequilibrium components using fundamental laws of thermodynamics and taking account of deformation phenomena for a solid, describe the state of an isothermally deformed metal specimen for all possible cases of uniaxial loading.2.Particular cases of characteristic Eqs. (1) permitting their integration with appropriate initial conditions have been considered. Solutions obtained for test cases of loading on alloy KhN70VMYuT and copper M1 give results close to experimental data. This points to the suitability of thermomechanical deformation entropy theory [1] for practical calculations of the relationship between stresses and strains over a period of time with isothermal uniaxial loading of specific materials. However, the set of basic experiments formulated, on whose basis coefficients for the characteristic equations were calculated, only makes it possible to describe processes deviating very little from the basic processes, and this significantly limits the area of reliability for these equations.

The results of a study of the evaporation of benzene, toluene, xylene, and butyl benzene emulsions in water are presented. An explanation is given of the kinetics involved in the evaporation of such emulsion drops in still air.

Results are shown of a study concerning the evaporation of tetrafluorodibromomethane within a temperature range from -14 to + 750°C.

Some experimental data on the effect of a helical triple-thread magnetic field on the development of the discharge, the conductivity, and the stabilization of the plasma-pinch position in the S-1 apparatus are presented. Values of Te=20 to 30 eV and Ti=10 eV, corresponding to a conductivity of the order of 1015 cgs units, are obtained. The helical field improves the development of the discharge and the heating of the plasma. On applying helical fields the plasma-containment time remains unchanged.

The determination of the strain trajectory from a known arbitrary loading trajectory is described within the framework of the theory of slip. Specific calculations have been made on an electronic computer.

1.The maximum strength of alloys of the system Al-Zn-Mg (Zn:Mg=1.7) is achieved after quenching and artificial aging; the aging effect for ultimate breaking strength of quenched alloys is ?sf=42-160 N/mm2.2.Microplastic deformation in Al-Zn-Mg alloys proceeds unevenly. In specimens after artificial aging or after quenching and artificial aging intercrystalline crack propagation is observed. Specimen failure in the quenched condition is mixed in nature. Alloys are not inclined towards overall or intercrystalline corrosion.

We have studied the ignition, combustion, and quenching temperatures of amyl alcohol at different positions of the liquid surface in the vessel. Quartz positions of the liquid surface in the vessel. Quartz tubes 22, 36, 56, and 80 mm in diameter were employed.