Sound Velocity in Liquid Binary Alloys as Calculated via the Percus-Yevick Liquid Phonon Dispersion Relation

Abstract

In this note, we utilize the recently calculatd long wavelength limit of the “liquid virtual crystal” model of binary alloy liquid structure factor at the melting temperature, ST_M ^AB (0), to estimate the long-volume binary liquid alloys. We compare the calculate sound velocities to the available experimental sound velocities in these liquid binary alloys and find reasonable agreement.     

Theoretical investigation of the viscosity of some liquid metals and alloys

The viscosities of some liquid metals and liquid binary alloys have been determined using the theoretical model developed by Morioka et al. (Z. Metallkd. 93, 4 (2002)). The model was applied successfully to the liquid mono-component metals Hg and Na and to the liquid binary alloys Hg–Na, Ag–Cu, Bi–Sn and Ag–Sb. The model successfully described the temperature dependence of viscosity for Hg and Na for a wide range of temperatures. The values of the adjustable parameters k and z were obtained for Hg and Na. For the liquid binary alloys, calculations were done at a particular temperature for each alloy and our results show that for Hg–Na and Ag–Cu there are both qualitative and quantitative agreements between calculated and experimental viscosity data. However, Bi–Sn and Ag–Sb manifested significant levels of quantitative discrepancies between calculated and experimental viscosity data.     

Electrical resistivity feature of Cu–Sn–(Bi) alloy melts

The temperature dependence of electrical resistivity of Cu–Sn alloys, along with Cu–Sn–Bi alloys, has been investigated in a wide temperature range using the DC four-probe technique. Evidently abnormal changes are observed on ρ–T curves of these alloys. The result reveals that the irreversible and reversible changes on these ρ–Tcurves indicate the existence of the metastable microinhomogeneous structure and microheterogeneous structure (including some short range orders) of the Cu–Sn and Cu–Sn–Bi alloy melts, respectively. Furthermore, the addition of Bi increases the metastable microheterogeneity in the first heating process of Cu–Sn melts.     

Behavior of the Surface Tension and the Viscosity in the Eutecticregion of the Liquid Feb alloy

Abstract

Thermodynamic and transport properties of pure liquid metals show interesting correlations near the melting temperature. This is well known for the case of the surface tension σ and the shear viscosity η In this paper we investigate the possible extension of these correlations to binary alloys, taking the FeB alloy as a case study. Based on literature data we analyze the variation of σ and η as a function of temperature and concentration in a deep eutectic region of the phase diagram of this alloy, as well as the possible correlations between those two quantities. Substantial differences with respect to the behavior in pure metals are found.     

Viscosity of Hg5Tl2 at 14.5°C

Abstract

By means of a toroidal oscillating viscometer, the shear viscosity of some mercury-thallium alloys has been measured in the composition range 28.5–29.5 atomic percent thallium and over the temperature range from 12.5–15.5°C. Some discussion of the experimental results is given in terms of liquid coordination number.     

Phonon Dispersion Curves of Some Liquid Metals Based on the Percus-Yevick Phonon Description

Abstract

Phonon dispersion curves are almost quantitatively predicted by a first-order theory based on a zeroth order model of independent density fluctuations. The temperature dependence of the liquid structure factor at constant volume is important for the present considerations.     

A Model of Resonance Scattering in Liquid Na[sbnd]Pb Alloys

Abstract

The curve of the electrical resistivity of liquid Na[sbnd]Pb alloys has a large maximum around the composition of Na₄Pb corresponding to a minimum value of the concentration-concentration fluctuation in the long wavelength limit, S_cc (0). The maximum in the resistivity curve is interpreted in terms of a resonance scattering of the conduction electrons by the short range ordered ‘complex’, based on the t-matrix formulation and with the help of thermodynamic data of these alloys.     

Viscosity of liquid Cu–Sn alloys

We investigated of the kinematic viscosity of liquid Cu–Sn alloys upon heating and subsequent cooling by the method of the oscillating cylinder. For the liquids alloys Cu75Sn25, Cu50Sn50, Cu48Sn52, Cu32Sn68, and Cu17Sn83, the temperature dependencies of the viscosity upon heating deviate from the Arrhenius relation. The temperature dependencies of viscosity show the Arrhenius-like behaviour upon cooling for all investigated alloys. A discrepancy between the temperature dependencies of viscosity obtained upon heating and cooling arised. We built the concentration dependences of the kinematic viscosity of liquid Cu–Sn alloys upon cooling. The increase of the values of viscosity and activation energy of viscous flow in the concentration range corresponding to the existence of intermetallic compounds Cu₃Sn in the solid state was observed. These results were qualitatively interpreted using the concept of microheterogeneities of liquid alloys.     

Improved Flory Formula for the Entropy of Mixing of Binary Liquids

Abstract

A simple model for the entropy of mixing of the compound forming binary alloys is proposed. It is shown that the entropy of the associates is proportional to the relative volume contraction of the liquid alloys.     

Virtual Crystal Model of Melting and the Structure Factor of Liquid Alloys

Abstract

In this paper, we extend the theory of melting entropy of metals, of Omini, based on the Percus-Yevick collective coordinate theory of liquids, to binary liquid alloys. We reformalate Omini's use of the Percus-Yevick theory to include binary liquid alloys and calculate the long wavelength limit of the binary liquid alloy structure factor as a function of solute concentration for the systems: Li-Na, K-Rb. Rb-Cs, Al-Zn, Zn-Ca and AI-Ga which are the most nearly equi-valent and equi-volumeatom pairs Omini worked with.     

Mwd Measurements of Liquid Crystalline Aromatic Polyesters by Gpc-Lalls Using A Mixed Solvent

Abstract

A GPC-LALLS method was developed to measure the molecular weight distribution(MWD) of liquid crystalline aromatic polyesters(LCPs). Pentafluolophenol and chloroform(35:65% by weight) as a mixed solvent was found to maintain the stability of LCPs solutions and to yild reliable GPC-LALLS curves for LCPs at room temperature.     

Surface Tension of the Liquid Hg-In Alloys

Abstract

The measurements of the surface tension of the liquid Hg-In alloys were made by means of a maximum drop pressure method. The surface tension increases monotonously with increasing the In concentration. It is thermodynamically shown that the composition of the Hg atoms adsorbed on the surface is larger than that in the bulk. Experimental results are compared with calculated results due to various model theories; in particular the hard sphere model with a density-dependent cohesive potential is found to be in qualitative agreement with experimental results of both surface tensions and its temperature coefficients.     

Thermodynamic Properties of Liquid Na-TI

Abstract

New measurements of the free energy and entropy of mixing and association thermodynamic properties of liquid Na-TI alloys at three temlperatures are reported. A thermodynamic model is developed and fitted to these with success but the failure of the model to fit the properties of Na-Ga is reported. The problems involved in fitting thermodynamic models are discussed.     

Enthalpies of mixing of liquid systems for lead-free soldering: Cu–Sb–Sn system

Using two different types of high temperature drop calorimeters, partial and integral enthalpies of mixing of liquid alloys were determined in the ternary Cu–Sb–Sn system. The system was investigated along four sections at 1100 K. Experimental data were used to find ternary interaction parameters by applying the Redlich–Kister–Muggianu model for substitutional solutions, and a full set of parameters describing the concentration dependence of the enthalpy of mixing was derived. From these, the isoenthalpy curves were constructed for 1100 K. The entire system shows exothermic enthalpy of mixing at the given temperature.     

Entropy of Mixing of Compound Forming Liquid Binary Alloys Using Flory's Formula

Abstract

We demonstrate how the formula we proposed recently for the effective volume can be applied to improve Flory's formula so that the entropy of mixing of liquid binary alloys can be determined theoretically with good accuracy. The results are distinctly better than in the hard sphere system for compound forming alloys.     

Structural Parameters of Inert Liquids: Part I. Liquid Helium,Neon and Xenon

Abstract

Radial distribution functions of liquid helium, neon and xenon at various temperatures and pressures published by different authors have been analysed by the method given before (Bagchi 1972). The relevant significant structural parameters of these liquids are given in the tables. The figures show how the theoretical curves fit the experimental curves and also show the distribution of individual neighbours.     

The abnormal changes of electrical resistivity in liquid Pb–In alloys

Electrical resistivity of liquid lead and indium (Pb–In) alloys with different compositions has been measured using the four-probe method in a large temperature range. Marked turning points on each resistivity–temperature (ρ–T) curve of the liquid Pb–In alloys can be observed far above the liquidus. The unusual variation of the resistivity of Pb–In melts suggests a structural transition of these melts, for resistivity is a sensitive parameter to the structure. Moreover, the DSC experiment of Pb–In melts supports the existence of a liquid–liquid (L–L) structure transition in Pb–In melts. Such a L–L structural transition can be described in terms of the gradual disappearance of atomic bonds corresponding to the crystal structure and/or to a reduction of the size of pre-formed atomic clusters. This implies an increase of disorder in the high temperature melts. The transition temperatures depend on the composition of Pb–In melts and the onset transition temperatures of the intermediate phase (α) Pb–63%In and Pb–70.6%In melts are higher than that of other compositions.     

Determination of Chelating Properties of Detergent Builders with the Calcium Selective Ion Electrode

Abstract

A liquid membrane calcium selective ion electrode was used to measure the free calcium content in equilibrium with calcium chelates. The chelating value, chelating curves, formation constants and equivalent weights of several detergent builders were calculated from these measurements.     

Electron spin resonance spectra and magnetic susceptibilities of mixed oxides,MUO3 (M; Li,Na, K,and Rb), of pentavalent uranium

In all magnetic susceptibility versus temperature curves for MUO₃ (M; Li, Na, K and Rb) a sharp spike appeared at 16–32 K. Magnetic susceptibilities are one order smaller than those of normal U(V) complexes. ESR spectra are very broad and have g-values of 2–4.     

The Absolute Thermoelectric Power of Some Dilute Liquid Sodium Alloys

Abstract

The absolute thermoelectric powers of liquid sodium and of dilute liquid alloys of sodium with silver, cadmium, indium and tin have been measured within the temperature range 100–460°C. The thermopower of liquid sodium is decreased by the addition of cadmium, indium or tin, with cadmium having the smallest and indium the greatest effect, whereas it is increased slightly on the addition of 1 at. % of silver. Values of the dimensionless thermopower parameter, ?, derived from the experimental data, are compared with those predicted by the Faber-Ziman theory; the agreement is quite good for Na-Ag and Na-Cd but less satisfactory for Na-In and Na-Sn. The discrepancies are discussed in terms of the assumptions involved in the calculations, namely the use of only one structure factor and local dielectric screening of the ionic pseudopotentials.