Deposition from the two-phase multicomponent flow of a vacuum-arc plasma containing droplets of an evaporated material

The interaction of a surface with the two-phase flow of a multicomponent vacuum-arc plasma containing droplets of an evaporated material along with multicharged ions and neutral atoms is studied. For the two-phase flow of a multicomponent plasma, the dependences of the ion-current density, the deposition rate, and the heat flow to a substrate on the bias voltage are obtained, and the conditions at which the coating deposition rate is inverted are determined. A unique probe technique for the plasma flow generated by an end-face Hall plasma accelerator with a “cold” eroded cathode is used to determine the volt-equivalent energy U** of the interaction of the two-phase plasma flows of Ti, Al, Cr, and an Ni-Cr-Al-Y alloy with a surface and the self-sputtering coefficient of the Ni-Cr-Al-Y alloy and its elements (Ni, Cr, Al) as a function of the bias voltage. Metallographic analysis is used to study the structure of thick (～100-μm) coatings deposited from the two-phase flow of a metallic multicomponent vacuum-arc plasma.     

Viscoplastic model for the strain resistance of 08Kh18N10T steel at a hot-deformation temperature

The viscoplastic model of the strain resistance of a metal developed earlier is shown to be applied to austenitic corrosion-resistant 08Kh18N10T steel with the fcc lattice at a hot-deformation temperature of 1150°C. Metallographic examination supports dynamic recrystallization occurring at this deformation temperature.     

Atomic ordering in the phases of a nickel-chromium-based superalloy

The distribution of alloying atoms over the sites of the ordered crystal lattices of the γ′ phase and the Ni₂Cr superstructure that form during aging of the EK78 superalloy is determined by neutron diffraction, and their long-range order parameters are measured. The size, shape, and orientation of the forming γ′-phase precipitates and the ordered matrix are determined by electron microscopy. The mechanism by which the ordered phases in the EK78 alloy form during complex heat treatment is described.     

Mechanism of the effect of the ferrite grain size on the fatigue strength of a low-carbon steel

The effect of the ferrite grain size on the fatigue strength of a low-carbon steel is studied. It has been shown that, as the ferrite grain size increases, the fatigue strength decreases due to plastic-flow localization. One of the explanations of this phenomenon is the beginning of the formation of periodical cellular dislocation structures.     

X-ray diffraction study of the structural evolution in a grade 1469 (Al-Cu-Li) alloy during the production of hot-rolled sheets

X-ray diffraction is used to study the structural changes in a grade 1469 (Al-Cu-Li) alloy with a high lithium content that occur during the production of hot-rolled sheets according to the ingot → pressed strip → hot-rolled sheet schedule. In the pressed strip, a multicomponent Bs {110}〈112〉, Cu {211}〈111〉, and S {123}〈111〉 texture forms, which is typical of articles pressed from such alloys, and an unusual intense single-component texture of the Ex₁ {011}〈111〉 type forms in the hot-rolled sheets. Its formation is stimulated by cross rolling of the sheets. The low strength characteristics of the hot-rolled sheets after heat treatment are related to an elevated heating temperature used for quenching and to the oriented precipitation of the lamellar particles of the hardening T ₁ phase.     

Processing of the rebellious polymetallic filizchai deposit ore using a combined technology

The results of studying the processing of rebellious polymetallic ores by a combined method are presented. The method combines the pyrometallurgical (pyrrhotinizing roasting) and hydrometallurgical (autoclave leaching with sulfuric acid) approaches. The proposed technology makes it possible to substantially enhance the degree of extraction of valuable components, simultaneously satisfying the requirements of the complex use of raw materials and the preservation of the environment.     

Corrosion resistance of vanadium alloys clad by a ferritic corrosion-resistant steel in liquid-metal heat-transfer agents

The results of studying the corrosion resistances of steels of various classes and vanadium-based alloys in liquid-metal heat-transfer agents (lithium, sodium, lead) are analyzed. These structural materials are shown to have satisfactory corrosion resistance in high-purity liquid metals. However, a nitrogen impurity in lithium and an oxygen impurity in sodium and lead cause the degradation of the mechanical properties and the fracture of the vanadium alloys. The use of these alloys clad by a ferritic corrosion-resistant steel is shown to ensure high corrosion resistance of the fuel-element can materials in fast neutron reactors with sodium and lead heat-transfer agents.     

Applicability of the laws of elasticity for the determination of the elastic-region length in the deformation zone during cold rolling

The errors of calculating the energy-force parameters of cold rolling are analyzed. They appear because of the assumption of the classic rolling theory about the applicability of the Hertz formula, which is known in the theory of elasticity, to the calculation of the elastic-region length in the deformation zone. The Hertz formula, which is used to calculate the half-width of the contact area between a fixed cylinder and a plane that bounds an elastic half-space, is shown not to take into account the following factors that are characteristic and important for the roll-strip contact: the cold working of the strip, the strip thickness, the rotation of rolls accompanied by sliding friction, and the wear that decreases the initial roll roughness (i.e., changes in the friction coefficient). A method is proposed for taking into account these factors in the calculation of the energy-force parameters of cold rolling; it is based on the statistical processing of the parameters that are measured in operating mills and are present in the databases of their process control systems. The application of this method decreases the errors of calculating the rolling forces by 35–40% and refines some laws of the state of stress in a rolled strip.     

Role of silicon in the formation of the corrosion resistance of austenitic materials for cryogenic engineering

The effect of silicon on the operational efficiency and corrosion resistance of low-temperature equipment made of 12Kh18N12T chromium-nickel steel has been studied. The specific features of the cryogenic equipment consist in high-temperature heating procedures between operation periods. Equipment for gas liquefaction and cleaning aimed at the restoration of the operational efficiency of filtration and catalysis systems serves as an example. The heating temperature of this equipment can reach 800°C. Experimental steels containing 0.09–1.03 wt % Si are subjected to intercrystalline corrosion tests. Upon heating to 550–600°C, silicon is found to increase the corrosion resistance of the steel, and, upon heating at higher temperatures, silicon plays a negative role. This is caused by the distribution of silicon atoms along grain boundaries, namely, a nonuniform silicon distribution with the formation of high-and low-concentration regions, i.e., the formation of clusters of silicon-phase preprecipitates.     

Mechanism of the structure formation of the transition layers in cobalt films electroplated on copper

The structure formation of the transition layers in electrolytic cobalt films on copper substrates is studied. It has been found that epitaxial growth and repeated twinning in the transition film/substrate layers form the nonequilibrium α and β cobalt phases, which cause additional reflections in electron and X-ray diffraction patterns.     

Formation of the limiting nanostructural state in metals during plastic deformation

The mechanisms that determine the formation kinetics of the limiting states in deformed solid nanostructures are considered. These states are characterized by the minimum average nanocrystallite size. The limiting states are shown to correspond to the point of dynamic equilibrium between the deformation-induced competing processes of nanograin fragmentation and growth.     

Electron-microscopic study of the slip systems in an Mg-4.5% Al-1% Zn alloy

Samples of a hot-rolled Mg-4.5% Al-1% Zn alloy plate cut normal to the rolling direction are studied to determine the density of dislocations with different Burgers vectors after warm rolling at low total strains. In the experiment, 22 different grains and their orientations are studied in a JEM-1000 high-voltage transmission electron microscope at an accelerated voltage of 750 kV using the WB DF technique (g, ng, where n = 2, 3, …) for the observation of dislocations. The main method used for the analysis of the Burgers vector of the dislocations is the invisibility criterion gb = 0. In the samples, dislocations with Burgers vectors 〈a〉, [c], and 〈a + c〉 are found. The dislocation dissociation reaction of the 〈a + c〉 dislocation into the 〈a〉 and [c] dislocations has been found for the first time, and an assumption is made that all of the found [c] dislocations result from this reaction. The density of the basal and nonbasal 〈a〉 dislocations does not depend on the orientation of the grains. Rarely found [c] and 〈a + c〉 dislocations are in grains whose orientations are near the texture maximum in the {0002} pole figure.     

Theory of Initial Microcavity Growth in a Liquid Metal Around a Gas - Releasing Particle. Part 2. Bubble Initiation Conditions and Growth Kinetics

A theory is presented that includes capillary, hydrodynamic, and diffusion aspects. The main attention is devoted to capillary and hydrodynamic effects. The hydrodynamic process (bubble growth) is governed by a nonlinear integrodifferential equation, whose coefficients are dependent on the surface tension, density, and viscosity of the liquid, and also on the difference between the pressure in the gas within the bubble and that in the surrounding liquid. The gas pressure in the bubble is dependent on the rate of gas release from the inclusion (source). An expression is derived for the bubble radius as a function of time. The theory can be useful for developing the technology of powder materials and foam metals.