Russian Metallurgy (Metally)最新文献

The influence of the deformation frequency in a low-cycle region (f = 1–3 Hz, N ≤ 10⁵ cycles) on the fatigue life characteristics of a nickel superalloy has been studied. Tests are performed under strain-controlled loading conditions at temperatures of 25 and 700°C. The influence of the deformation frequency on the fatigue life is found to be most significant at an elevated temperature. The main difference in the character of fracture consists in a flatter fracture surface relief and a longer fatigue crack front at an increased loading frequency.

Some theoretical foundations and structural factors of the strain hardening of metals and alloys over a wide temperature range are analyzed. Practical methods for controlling the balance of strength and ductility of alloys of various chemical compositions using deformation and thermomechanical methods of influencing a structure are proposed.

Abstract—The composition, structure, and properties of a lead–antimony alloy sintered from an electroerosive powder produced in burning kerosene are experimentally studied. The use of spark plasma sintering to manufacture products from the powder produced by electrodispersion of an SSu3 alloy allows us to recommend such alloys for the production of current collector plates of lead car batteries due to higher anticorrosive properties compared to the initial alloys; low porosity, which allows us to increase the contact area with lead coating to improve the adhesion; and high, for nonferrous alloys, microhardness, ensuring a long service life of lead grids.

Metallographic and tribological (under dry sliding friction conditions) investigations of low-alloy steel samples with an overequilibrium nitrogen content are performed after quenching in the temperature range from (Ac₃ – 50) to (Ac₃ + 250)°C. Metallographic analysis demonstrates that, as the quenching temperature increases, the grain size increases and the dispersion of the martensitic structure decreases. The results of tribological studies demonstrate that, after quenching in the temperature range (Ac₃ + 100)–(Ac₃ + 150)°C, the content of austenite saturated with carbon and nitrogen increases, which leads to a decrease in the coefficient of friction and an increase in the wear resistance.

A mathematical model is proposed for the thermal interaction between a moving energy source in a coaxial slag bath and all moving media, such as cooling water, consumable electrode, welded hollow ingot, and liquid metal bath. The obtained model is evaluated by comparing theoretical and experimental data.

The laws of changing the shape of cylindrical springs made of a titanium nickelide-based alloy are considered as a function of the level of counteracting stresses and thermal cycling boundaries. Stresses from 20 to 110 MPa are shown to cause completely reversible deformation of the material; at higher stresses, unrecovered deformation accumulates. During thermal cycling, a decrease in heating temperatures in the range A_s–A_f and an increase in cooling temperatures in the range M_s–M_f are accompanied by a decrease in the reversible deformation of the material.

Abstract—The kinetic laws of Fe³⁺ ion electroreduction in the KCl–NaCl–CsCl eutectic melt at 823 K are determined. The potentials of metallic iron and dysprosium formation on the inert tungsten electrode in the KCl–NaCl–CsCl molten system are found to differ by approximately 1.5 V. In the case of the combined presence of Fe³⁺ and Dy³⁺ ions in the KCl–NaCl–CsCl eutectic melt, a certain depolarization of dysprosium ion electroreduction occurs on the metallic iron preliminary deposited at the tungsten electrode to form iron- and dysprosium-based intermetallic phases of different compositions. The dissolution potentials of the different intermetallic phases Dy_xFe_y are determined by open circuit chronopotentiometry.

Alloys of the nickel–cobalt system are widely used in industry. Boron is one alloying constituents of the alloys. The study of the thermodynamics of oxygen solutions in boron-containing Ni–Co melts is of substantial interest for manufacturing practice. Thermodynamic analysis of the oxygen solutions in the boron-containing Ni–Co melts is performed. The equilibrium constants of the reaction of boron with oxygen dissolved in the Ni–Co melts, the activity coefficients at infinite dilution, and the interaction parameters for the melts differing in the composition are determined at 1873 K. The interaction parameters are calculated; these are (varepsilon _{{{text{B(Ni)}}}}^{{{text{Co}}}}) = –0.238 and (varepsilon _{{{text{B(Co)}}}}^{{{text{Ni}}}}) = 0.674. When boron interacts with oxygen in the Ni–Co melts, the oxide phase contains the NiO and CoO oxides along with B₂O₃. The molar fractions of B₂O₃, NiO, and CoO in the oxide phase are calculated for different boron concentrations in the Ni–Co melts at 1873 K. In the case of the nickel melt with boron contents of more than 0.01%, the molar fraction of boron oxide is close to unity. As the cobalt content in the melts increases to 20%, the molar fraction of boron oxide in the oxide phase decreases and then is almost unchanged. The dependences of the oxygen solubility in the studied melts on the cobalt and boron contents are calculated. The deoxidizing ability of boron slightly decreases as the cobalt content increases to 20%, and after that increases as the cobalt content in the melt increases. The boron concentrations corresponding to the minima in the oxygen solubility curves and associated minimum oxygen concentrations are determined.

Abstract—The high-temperature oxide–metal melts that form in cold crucible induction melting (CCIM) furnaces. The results of pilot tests in CCIM furnaces at melt temperatures above 2400°C in air, which are conducted to study the distribution of components between the oxide and metal phases of a two-phase melt with limited component miscibility, are presented. The results of physicochemical studies of the materials fabricated by quenching solidification of a high-temperature melt are presented, and they confirm the reduction of silicon and the oxidation of iron with the redistribution of these components between the oxide and metal phases. This experimental result contradicts the well-known Ellingham diagrams and thermodynamic calculations, but a similar effect is experimentally observed in the U–O–Fe system. Thus, the CCIM method allows the inversion of redox processes in a number of oxide–metal systems, which can be used to produce new materials and to create technologies for high-temperature extraction of target components.

Abstract—The slurry coatings fabricated by aluminizing and aluminosiliconizing using a binder consisting of colorless nitrolacquer and a solvent are studied. The replacement of a binder based on nitrocellulose dissolved in amyl acetate and diethyloxalate by the NTs-62 nitrolacquer with solvent no. 646 is found to ensure the production of high-quality protective coatings by the slip method using aluminizing and aluminosiliconizing. Isothermal heat-resistance tests in air at 1100°C for 200 h have confirmed high protective properties of the coatings fabricated by aluminizing and aluminosiliconizing. Using the Davidenkov method, we find that residual compressive stresses at a depth of 20–30 μm are induced in the coatings fabricated by aluminizing and aluminosiliconizing by the slip method with the new binder composition (NTs-62 lacquer + solvent no. 646).