Study of Effect of Non-Metallic Inclusions on Structural State and Properties of Low-Carbon Microalloyed Structural Steels

Metallurgist - The effect of silicate glassy inclusions, formed in the final stages of ladle treatment and during continuous casting, on the structural state of cast billets and the properties of...     

Study of Conditions for Improving Chemical and Structural Homogeneity of Ferritic Class Hot-Rolled Steels

Metallurgist - Redistribution of carbon and other elements, and formation of the structure, composition, and properties of low-carbon Nb, Nb–Ti, Nb–V, Nb–V–Mo and...     

Energy content of the nonexplosive excavation of rock by excavators with a dynamic scoop

Conclusions  

Evaluation of the quality of GaAs epitaxial layers and their interfaces from analysis of the exciton absorption spectra

Exciton optical spectra are sensitive to even slight changes in the properties of a solid. The spectra of exciton polaritons can be especially informative, although the spectroscopy of these quasiparticles imposes certain restrictions on the measurement temperature and the quality of the material. Exciton parameters such as the resonance frequency ω _T and damping coefficient Γ may vary under the influence of electric fields, defects present in the crystal, or changes in the chemical composition of the film. If the material characteristics vary along the thickness of the film (the z coordinate), so do the resonance frequency and damping coefficient. Here, the spectra of undoped GaAs layers epitaxially grown on GaAs substrates are investigated at T = 1.7 K. Analysis of the spectra at the exciton absorption edge makes it possible to estimate the “dead-layer” depth, the strength of electric fields, and the concentration of impurities.     

Application of the diagrams of phase transformations during aging for optimizing the aging conditions for V1469 and 1441 Al-Li alloys

To describe the changes in the phase composition of alloys during aging, it is convenient to construct TTT diagrams on the temperature-aging time coordinates in which time-temperature regions of the existence of nonequilibrium phases that form during aging are indicated. As a rule, in constructing the diagrams of phase transformations during aging (DPTA), time-temperature maps of properties are plotted. A comparison of the diagrams with maps of properties allows one to analyze the effect of the structure on the properties. In this study, we analyze the DPTAs of V1469 (Al-1.2 Li-0.46 Ag-3.4 Cu-0.66 Mg) and 1441 (Al-1.8 Li-1.1 Mg-1.6 Cu, C _Mg/C _Cu ≈ 1) alloys. Examples of the application of DPTA for the development of steplike aging conditions are reported.     

Experimental study of the temperature dependence of the permittivity of nanocomposite materials based on a low-density polyethylene matrix with iron nanoparticles

The temperature dependence of the dielectric permittivity of nanocomposites based on a high-pressure (low-density) polyethylene matrix with various concentrations of dispersed iron nanoparticles (2–22 wt %) has been studied. As the temperature increases from 0 to 40°C, the permittivity decreases for all concentrations of nanoparticles in the range studied. The results can be useful for developing thermostable acoustic waveguides.     

Calculation method for the unsteady air supply in mine ventilation networks

The problem on one-dimensional unsteady compressed air flow in an arbitrary topology mine is solved using a mathematical model, including one-dimensional equations and pressure-velocity continuity condition, the method of characteristics, difference scheme and the AEROSET software.