Viscosity of liquid Co–Sn alloys: thermodynamic evaluation and experiment

Shear viscosity measurements were performed for liquid Co–Sn alloys over a wide temperature range above the respective liquidus temperatures. A high temperature oscillating-cup viscometer was used. It was found experimentally that viscosity as a function of temperature obeys an Arrhenius law. The data were compared with calculated values, obtained from different thermodynamic approaches. A good agreement was found between experimental results and calculated ones by the Budai–Benkö–Kaptay model.     

Surface tension of liquid high-entropy equiatomic alloys of a Cu–Sn–Bi–In–Pb system

An experimental study of the temperature dependences of the surface tension of liquid high-entropy equiatomic alloys of a Cu–Sn–Bi–In–Pb system is conducted. Measurements are made within the temperature range of t _L to 1300°C in the mode of heating and subsequent cooling of a sample. Overcooling of a melt prior to crystallization is detected. The depth of overcooling grows along with the number of components in the melt, while the temperature coefficient of surface tension falls. The experimental results qualitatively interpreted within the concepts of the specific surface entropy of a liquid.     

Microstructural properties of sintered Al–Cu–Mg–Sn alloys

A non-commercial Al4Cu0.5Mg alloy has been used for investigating the effects of the elemental Sn additions. Uniaxial die compaction response of the alloys in terms of green density was examined, and the results showed that Sn addition has no effect when compacting conducted under high pressures. In total, 93–95% green density was achieved with an applied pressure of 400 MPa. Thermal events occurring during the sintering of the emerging alloys were studied by using differential scanning calorimetry (DSC). First thermal event on the DSC analysis of the Al4Cu0.5Mg1Sn alloy is the melting of elemental Sn, whereas for Al4Cu0.5Mg alloy, it is the formation of Al–Mg liquid nearly at 450 °C. Also it is clearly seen on the DSC analysis that Sn addition led to an increase in the formation enthalpy of Al–Mg liquid phase. High Sn content and high sintering temperature (620 °C), therefore high liquid-phase content, caused decrease on the mechanical properties due to thick intergranular phases and grain coarsening. Highest transverse rupture strength and hardness values were obtained from Al4Cu0.5Mg0.1Sn alloy sintered at 600 °C and measured as 390 MPa and 73 HB, respectively.     

Electrical conductivity and thermoelectric power of liquid Co–Sn alloys

The electrical conductivity and thermoelectric power of liquid Co–Sn alloys were investigated in a wide concentration and temperature range. It was shown that the electrical conductivity of the melts decreased with an increase of the Co content. The results are interpreted in the context of the s–d hybridisation model. The corresponding behaviour is caused by sharing electrons from one metal to another one. This is in agreement with the concept of Fermi enthalpy, according to which up to two electrons from Sn transfer to the uppermost bands of Co.     

Thermodynamic analysis of liquid In–Sn alloys using Oelsen calorimetry

The results of calorimetric investigations of liquid In–Sn alloys using Oelsen calorimetry are presented in this article. Based on obtained enthalpy space diagram and enthalpy isotherm diagram, thermodynamic parameters for the liquid In–Sn alloys, including mixing and excess integral and partial molar quantities at temperature of 600 K, have been determined and compared with available literature data.     

The density and surface tension of In–Sn and Cu–In–Sn alloys

Abstract  

The density and surface tension of binary In–Sn and ternary Cu–In–Sn alloys have been measured by a sessile-drop method. Decrease of the density and of the surface tension was observed with rising temperature. With increased Sn content in the alloys, the density increased while the surface tension reduced slightly. Addition of Cu could significantly increase the density and surface tension in the Cu–In–Sn system. The surface tension of the Cu–In–Sn alloys was also calculated by means of Butler’s equation, and compared with experimental values, showing good agreement.     

Surface properties and wetting characteristics of liquid Ag–Bi–Sn alloys

Abstract  

Surface tension and density measurements of liquid Ag–Bi–Sn alloys were carried out over a wide temperature range using the sessile drop method. The experimental data of surface tension were analyzed by the Butler thermodynamic model in the regular solution approximation. The Sn-rich Ag–Bi–Sn liquid alloys show better wetting behavior on the Cu substrates as compared to the Ni substrates.     

Viscosity of liquid alloys: generalization of Andrade’s equation

Abstract  

The Andrade relation for the viscosity of liquid metals has been reformulated in terms of the Debye temperature for liquid metals. This semi-empirical relation has been extended to obtain a relation to calculate the composition and temperature dependence of the viscosity of liquid alloys using parameters which can be determined experimentally. The important inputs are the enthalpy of formation, ΔH, and the excess volume of mixing, ΔΩ. The composition dependence of the viscosity and its deviation from linear behavior could be positive or negative depending on the sign and magnitude of ΔH and ΔΩ. Several limiting cases of the semi-empirical relation for the viscosity of liquid alloys are compared and discussed. The results of the semi-empirical relation for viscosity isotherms for binary and ternary liquid alloys are mostly in reasonable agreement with available experimental results.     

Thermodynamic evaluation of viscosity in In–Zn and Sn–Zn liquid alloys

A theoretical formalism that links thermodynamic properties to transport properties has been used to study the viscosity of Sn–Zn and In–Zn liquid alloys at various temperatures. The formalism was successful at describing the thermodynamic properties of these alloys and showed a better estimation of the viscosity of the Sn–Zn alloy than that of the In–Zn alloy.     

Thermodynamics and vacuum distillation studies of liquid Al–Ga and In–Sn alloys

Activities of components in liquid Al–Ga and In–Sn alloys, the separation coefficients and vapour–liquid phase equilibrium in vacuum distillation were predicted using the molecular interaction volume model as a function of the activity coefficients. The results indicated that both Al and In are preferentially volatilised into vapour phase while Ga and Sn remain in residue. Similarly, we found that both the mass fraction and the content of Al and In in vapour phase increase as distillation temperature increases such that when the content of Al is 0.005985 wt% and In is 0.004141 wt% in vapour phase, respectively, in liquid phase, it was 70 wt% at T = 1073 K for both. The calculated values of activity and activity coefficients at various temperatures are presented. Comparison of the predicted values with experimental data indicates good agreement, thus verifying from statistical thermodynamics viewpoint that the model is stable and reliable.     

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.     

Mixing enthalpy of liquid Cu–Hf–Ni alloys at 1873 K

Journal of Thermal Analysis and Calorimetry - The mixing enthalpies of liquid Cu–Hf–Ni alloys were determined at 1873 K by applying a high-temperature isoperibolic calorimeter....