The presence of artifacts in thermodynamic and structural properties of the Al–Mn liquid alloy at higher temperatures has been investigated assuming the interaction parameters present in the modeling ...equations to be linearly and exponentially temperature dependent. When the concept of linear temperature dependence of interaction parameters is employed to explain the thermo-structural properties of the Al–Mn liquid alloy some asymmetric artifacts appear in these properties at higher temperatures. However, these artifacts are successfully eliminated from the thermo-structural properties of the Al–Mn liquid alloy when the interaction parameters present in the modeling equations are considered to be exponentially temperature dependent.
Thermodynamic and surface properties of Ti-Al-Fe liquid ternary alloy have been assessed at temperatures 1873 K, 1973 K, 2073 K and 2173 K. The thermodynamic properties, such as activity have been ...studied using general solution model (GSM) and excess free energy of mixing has been studied using GSM, Kohler and Toop models. In surface properties, surface concentration has been computed using Butler's equation and surface tension of the liquid alloy has been studied using all the four above mentioned models feeding the database of liquid Ti-Al, Al-Fe and Ti-Fe sub-binary systems. The values of surface tension computed using GSM and Toop model are in well agreement with each other at all concentrations. Moreover, the computed values of excess free energy of mixing and surface tension decrease at elevated temperatures from all corners and at all considered cross-sections indicating the decrease in mixing tendency of the alloy.
The surface tension and viscosity of Cu–Fe–Si ternary alloys were computed at different temperatures using thermodynamic approaches. The thermodynamic data of the alloy were optimized in the ...framework of the Redlich-Kister (R–K) polynomials and exponential temperature dependent coefficients of the R–K polynomial were obtained. These coefficients were used to compute the excess Gibbs free energy of mixing of the alloy and the partial excess free energy of the components. The partial excess free energy so obtained was used to compute the surface tension of the ternary Cu–Fe–Si alloy system and its binary sub-systems. The enthalpy of mixing was also optimized and it was used to compute the viscosity of the sub-binary and ternary alloys.
Condensed matter physics, Materials science, Thermodynamics, Cu–Fe–Si ternary alloy, Exponential temperature dependent parameters, Surface tension, Surface concentration, Viscosity.
The thermodynamic and structural properties of Fe - based (Al-Fe and Fe-Si) alloys in their liquid states at different higher temperatures have been studied assuming the interaction parameters of R-K ...polynomial are linearly and exponentially dependent on temperature. It has been observed that artificial miscibility gaps (also called artefacts) appear in the thermodynamic and structural properties of the aforementioned alloys at high temperature when the interaction parameters are assumed to be linearly dependent on temperature. The artificial miscibility gaps or artefacts observed in the former case are eliminated when the interaction parameters are supposed to be exponentially dependent on temperature. This implies that the interaction parameters of RK-polynomial for liquid alloys vary exponentially at elevated temperatures.
Muons produced in atmospheric cosmic ray showers account for the by far dominant part of the event yield in large-volume underground particle detectors. The IceCube detector, with an instrumented ...volume of about a cubic kilometer, has the potential to conduct unique investigations on atmospheric muons by exploiting the large collection area and the possibility to track particles over a long distance. Through detailed reconstruction of energy deposition along the tracks, the characteristics of muon bundles can be quantified, and individual particles of exceptionally high energy identified. The data can then be used to constrain the cosmic ray primary flux and the contribution to atmospheric lepton fluxes from prompt decays of short-lived hadrons.
In this paper, techniques for the extraction of physical measurements from atmospheric muon events are described and first results are presented. The multiplicity spectrum of TeV muons in cosmic ray air showers for primaries in the energy range from the knee to the ankle is derived and found to be consistent with recent results from surface detectors. The single muon energy spectrum is determined up to PeV energies and shows a clear indication for the emergence of a distinct spectral component from prompt decays of short-lived hadrons. The magnitude of the prompt flux, which should include a substantial contribution from light vector meson di-muon decays, is consistent with current theoretical predictions.
The variety of measurements and high event statistics can also be exploited for the evaluation of systematic effects. In the course of this study, internal inconsistencies in the zenith angle distribution of events were found which indicate the presence of an unexplained effect outside the currently applied range of detector systematics. The underlying cause could be related to the hadronic interaction models used to describe muon production in air showers.
The thermodynamic and structural properties of Cu–Si liquid alloys were computed at different temperatures assuming that the interaction parameters were linearly and exponentially dependent on the ...temperature in the framework of R–K polynomials. Both these assumptions were found appropriate in explaining the mixing properties of the alloy near the melting temperature. However, the assumption of the linear temperature dependence of interaction parameters could not explain the properties of the alloy when the temperature was elevated. The exponential temperature dependence of the interaction parameters was found successful in explaining the thermodynamic and structural properties of the alloys over a large temperature range.
We have employed quasi-chemical approximation to study the concentration dependence of bulk thermodynamic properties of two liquid alloys, Co–Fe and Fe–Pd at temperatures of 1863K and 1873K, ...respectively, at fixed atmospheric pressure. In order to investigate the surface structure in the alloys we have also performed a comparative study of surface tension using two statistical models. The study of the alloys indicates a positive deviation from the Raoultian behaviour with a higher degree of segregation in Fe–Pd system than that in the Co–Fe system. The surface tension is found to increase, both in Co–Fe and Fe–Pd alloys, with the addition of Fe-component. Furthermore, the surface segregation of the atoms of the metal with lower surface tension (Pd atoms in Fe–Pd alloy and Co atoms in Co–Fe alloy) is pronounced. Maximum surface segregation is expected to occur in the Co–Fe and Fe–Pd alloys around the compositions xCo=0.5 and xFe=0.8, respectively.
•Co–Fe and Fe–Pd alloys in liquid state are segregating in nature.•Ordering energy for both of these is temperature dependent.•The atoms of the metals with lower surface tension tend to segregate in the surface.
Temperature-dependent interaction parameters of Redlich-Kister (R–K) polynomials for Li–Mg alloy in liquid phase have been optimized using experimental data in the framework of linear and exponential ...models. These parameters have then been used to compute the thermodynamic properties (excess Gibbs free energy of mixing, enthalpy of mixing and activity) and structural property (concentration fluctuations in the long-wavelength limit) of the alloy at temperatures 1000 K, 1300 K, 1600 K, 1900 K, and 2200 K. The negative values of excess Gibbs free energy of mixing computed using linear T-dependent parameters increases with the rise in the temperature of the system beyond 1000 K while the same physical quantity computed using the exponential T-dependent interaction parameters decreases with the rise in temperatures and does not show any unusual trends up to 2200 K. Similar behavior has been found in the case of other thermodynamic and structural functions. The unusual behavior that appears in the thermodynamic and structural functions computed using linear T-dependent parameters can be eliminated if these functions are computed using exponential T-dependent parameters.
Li-Mg alloy; R–K polynomial; Exponential parameters; Miscibility gap; High temperature
PDF
