Binary system

About: Binary system is a research topic. Over the lifetime, 5788 publications have been published within this topic receiving 97882 citations.

Experimental and thermodynamic studies of the Fe-Si binary system

Abstract: Phase equilibria in the Fe–Si binary system were investigated experimentally and thermodynamic assessment was carried out. The αFe (A2) + α"Fe3Si (D03) two-phase microstructures at 600°C and 650°C were obtained, whose grain sizes were sufficiently coarsened to be analyzed by FE-EPMA with a spatial resolution below 0.5 μm under the condition of 6 kV accelerating voltage. α'FeSi (B2) + α"Fe3Si (D03) two-phase equilibria above 700°C were detected for the first time and equilibrium compositions were determined by the diffusion couple method. The horn-shaped two-phase miscibility gap extends from the low temperature αFe + α"Fe3Si equilibrium along the B2/D03 second-order transition boundary and closes below 1000°C. Four-sublattice split compound energy formalism was applied to calculate the Gibbs energy of the bcc phases, A2(αFe), B2(α'FeSi) and D03(α"Fe3Si), and the thermodynamic parameters in the Fe–Si binary system were evaluated. Equilibrium relations in the binary system were well reproduced, especially the effect of the B2 and D03 ordering on the liquidus and solidus curves and the miscibility gap between bcc phases. Optimized thermodynamic parameters as well as the experimental results are expected to be helpful for developing higher multi-component systems for practical steels.

Misaligned gas discs around eccentric black hole binaries and implications for the final-parsec problem

Abstract: We investigate the evolution of low mass (Md /Mb = 0.005) misaligned gaseous discs around eccentric supermassive black hole (SMBH) binaries. These are expected to form from randomly oriented accretion events onto a SMBH binary formed in a galaxy merger. When expanding the interaction terms between the binary and a circular ring to quadrupole order and averaging over the binary orbit, we expect four non-precessing disc orientations: aligned or counter-aligned with the binary, or polar orbits around the binary eccentricity vector with either sense of rotation. All other orientations precess around either of these, with the polar precession dominating for high eccentricity. These expectations are borne out by smoothed particle hydrodynamics simulations of initially misaligned viscous circumbinary discs, resulting in the formation of polar rings around highly eccentric binaries in contrast to the co-planar discs around circular binaries. Moreover, we observe disc tearing and violent interactions between differentially precessing rings in the disc significantly disrupting the disc structure and causing gas to fall onto the binary with little angular momentum. While accretion from a polar disc may not promote SMBH binary coalescence (solving the `final-parsec problem'), ejection of this infalling low-angular momentum material via gravitational slingshot is a possible mechanism to reduce the binary separation. Moreover, this process acts on dynamical rather than viscous time scales, and so is much faster.

Phase Diagram of the BaO-CuO Binary System

Abstract: The phase diagram of the BaO-CuO binary system has been investigated in air and in a mixed gas of Ar + 0.21 atm of O2. The existence of two compounds, BaCuO2 and Ba2CuO3, was confirmed. The phase transition of Ba2CuO3 from an orthorhombic to a tetragonal phase was observed to occur at 1083 K. The lattice constants of the tetragonal Ba2CuO3 phase were determined to be a= 1.2975 nm and b= 0.3992 nm. BaCuO2 was shown to melt incongruently by a synthetic reaction at 1289 K. Furthermore, the existence of two eutectic reactions and a peritectic reaction in the present system was confirmed.

Binary adsorption equilibrium of carbon dioxide and water vapor on activated alumina.

Abstract: Adsorption equilibria of a CO2/H2O binary mixture on activated alumina F-200 were measured at several temperatures and over a wide range of concentrations from 4% to around 90% of the saturated water vapor pressure. In comparison with the single-component data, the loading of CO2 was not reduced in the presence of H2O, whereas at low relative humidity the adsorption of H2O was depressed. The binary system was described by a competitive/cooperative adsorption model where the readily adsorbed water layers acted as secondary sites for further CO2 adsorption via hydrogen bonding or hydration reaction. The combination of kinetic models, namely, a Langmuir isotherm for characterizing pure CO2 adsorption and a BET isotherm for H2O, was extended to derive a binary adsorption equilibrium model for the CO2/H2O mixture. Models based on the ideal adsorbed solution theory of Myers and Prausnitz failed to characterize the data over the whole composition range, and a large deviation of binary CO2/H2O equilibrium from ideal solution behavior was observed. The extended Langmuir-BET (LBET) isotherm, analogous to the extended Langmuir equation, drastically underestimated the CO2 loading. By incorporating the interactions between CO2 and H2O molecules on the adsorbent surface and taking into account the effect of nonideality, the realistic interactive LBET (R-LBET) model was found to be in very good agreement with the experimental data. The derived binary isosteric heat of adsorption showed that the heat was reduced by competitive adsorption but promoted by cooperative adsorption.