W. Gasior

Surface tension of liquid Ag-Sn alloys: Experiment versus modeling

The maximum bubble pressure method has been used to measure the surface tension of pure tin and seven binary alloys with concentrations of 15, 30, 40, 60, 75, 87.8, and 96.2 at.% Sn. Measurements were performed at the temperature range from 500 to about 1400 K depending on the composition of the investigated alloy. Densities of the Ag-Sn alloys were measured dilatometrically. The linear dependencies of densities and surface tensions on temperature were observed, and they are described by a straight-line equation.

Thermodynamic studies and the phase diagram of the Li-Mg system

By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1) / LiCl-LiF (eut) or LiCi-KCl (eut) / Li-Mg (1) or Li (1) / LiCl-LiF (eut) / Li-Mg (s) Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 to 0.45 molar fractions, respectively. Studies on solid alloys enabled us also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.

Calorimetric and emf studies on liquid Li-Sn alloys

By means of high temperature calorimetry the mixing enthalpies ΔH of liquid Li-Sn alloys have been measured; however, due to experimental problems they were determined only forxLi = 0.01 to 0.5 andxLi = 0.87 to 0.99. The range of temperatures studied was 691 to 938 K. High compound forming tendency in Li-Sn is reflected by a triangular-shaped relation for ΔH vs xLi. The extrapolated maximum of this plot is about −40 kJ mol−1 close to Li4Sn. Using the concentration cell Bi(l)Li3Bi(s)¦ LiF-LiCl¦Li-Sn(l) the emf was measured as function of temperature (775 to 906 K) atxLi = 0.1 to 0.603 enabling calculations of partial thermodynamic data for lithium in liquid Li-Sn solutions. Integral enthalpies calculated from partial enthalpies of lithium correspond well to the calorimetrically obtained integral mixing enthalpies in the concentration range where both emf and calorimetric data were obtained. The extrapolated maximum of ΔH from calorimetric studies and minimum of integral excess entropies from emf measurements correlate well with results of structure measurements and of other structure sensitive properties. All this experimental information indicates a maximum chemical short range order close to the composition Li4Sn.

Thermodynamic studies and the phase diagram of the Li-Sn system

By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1) / LiCl-LiF (eut) or LiCi-KCl (eut) / Li-Mg (1) or Li (1) / LiCl-LiF (eut) / Li-Mg (s) Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 to 0.45 molar fractions, respectively. Studies on solid alloys enabled us also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.

Evaluation of the influence of Bi and Sb additions to Sn-Ag-Cu and Sn-Zn alloys on their surface tension and wetting properties using analysis of variance -ANOVA

Purpose – The purpose of this paper is a comparable evaluation of the influence of a particular element (Bi and Sb) added to Sn‐Ag‐Cu and Sn‐Zn alloys on their surface and interfacial tensions, as well as the wetting properties on the Cu substrate expressed by the wetting angle.Design/methodology/approach – The authors applied the L8 orthogonal Taguchi array to carry out the experiments and discussed the results using analysis of variance (ANOVA).Findings – It was expected, on the base of previous studies, the decrease of the surface and interfacial tensions and thus improving wettability after the Bi and Sb addition to Sn‐Ag‐Cu and Sn‐Zn alloys. Unfortunately, the obtained results on the quinary Sn‐Ag‐Cu‐Bi‐Sb alloys and the quaternary Sn‐Zn‐Bi‐Sb alloys do not confirm these trends. The performed analyses suggest that the compositions of the quinary Sn‐Ag‐Cu‐Bi‐Sb alloys, as well as the quaternary Sn‐Zn‐Bi‐Sb alloys, do not have optimal compositions for practical application. The Cu, Bi and Sb elements i...

Surface Tension, Density, and Molar Volume of Liquid Sb-Sn Alloys: Experiment Versus Modeling

Through the application of the maximum bubble pressure and dilatometric method, density and surface tension were investigated. The experiments were conducted in the temperature range from 583 K≤T≤1257 K. The surface tension was measured for pure antimony and for six liquid Sb-Sn alloys (mole fractions XSn=0.2, 0.4, 0.6, 0.8, 0.9, and 0.935 mm2) and measurements of the density were only for alloys. It has been observed that both surface tension and density show linear dependence on temperature. The temperature-concentration relation of both surface tension and density were determined with minimization procedures. The surface tension isotherms calculated at 873 K and 1273 K show slight negative deviations from linearity changes, but the observed maximal differences did not exceed 30 mN · m−1. The surface tension calculated from Butler’s model was higher than the experimental value for most concentrations and also showed curvilinear temperature dependence. The experimental densities and the molar volumes of the Sb-Sn liquid alloys conform very closely to ideal behavior with differences comparable to the experimental errors.

Bulk and Surface Properties of Liquid Al-Li and Li-Zn Alloys

Physicochemical properties like density, surface tension, and viscosity of liquid binary Al-Li and Li-Zn alloys have been measured using draining crucible method. The experimentally measured surface-tension values have been compared to theoretical results based either on the Butler model or the compound formation model assuming the existence of the most favored A1B2 and A2B3 clusters. Several models for viscosity calculation have been also applied and discussed in confrontation with measured data. Finally, the clustering effects in the liquid Al-Li and Li-Zn alloys have been examined using two microscopic functions, i.e., the concentration fluctuation function in the long-wavelength limit and the Warren-Cowley short-range order parameter.

Densities of solid aluminum-lithium (Al-Li) alloys

Densities of solid Al and Al-Li alloys were measured by the dilatometric method for six compositions of mole fractions of lithium: 0.05,0.1,0.125,0.15,0.20, and 0.25. A curvilinear dependence of density on temperature (room temperature up to 923 K) was observed for all investigated alloys. Results could be described by parabolic equations. The molar volumes of Al-Li alloys were calculated from the density measurements. It has been found that the densities of solid Al-Li alloys initially show slightly negative deviations from linearity that reverse to positive above 0.075 mole fraction of Li. Molar volume exhibits negative deviation from linear dependence for all samples in the experimental concentration range. Power series were used to fit the dependences of density on temperature and concentration. Coefficients of volume expansion were calculated and discussed. The density of the β phase along the (α + β)/β boundary was calculated and described by a temperature-dependent polynomial.

Database of Pb - free soldering materials, surface tension and density, experiment vs. Modeling

Experimental studies of surface tension and density by the maximum bubble pressure method and dilatometric technique were undertaken and the accumulated data for liquid pure components, binary, ternary and multicomponent alloys were used to create the SURDAT data base for Pb-free soldering materials. The data base enabled, also to compare the experimental results with those obtained by the Butler’s model and with the existing literature data. This comparison has been extended by including the experimental data of Sn-Ag-Cu-Sb alloys.

Al-Cu-Li system electromotive force and calorimetric studies-Phase diagram calculations of the Al-Rich part

Electromotive force (emf) studies were made for solid and liquid AI-Cu-Li alloys. Measurements were conducted on four sets of alloys at temperatures and composition ranges as follows (where XLi is mole fraction): T/K XAl/XCu Li Composition Range 888 9 0.001 ≤XLi ≤ 0.639 888 4 0.013 ≤XLi ≤ 0.815 828 7/3 0.0001 ≤ XLi ≤ 0.5 778 7/3 0.0032 ≤ XLi ≤ 0.639 For these alloys, the Li concentration was introduced into an alloy by coulometric titration. Supplementary emf measurements were made at 828 K on 23 pyrometallugically prepared alloys with XA1/XCu=7/3 and with a XLi range of 0.05≤XLi≤0.639. Good agreement was observed between the results from this set of alloys and the results from alloys prepared by coulometric titration. Drop calorimetric studies also were performed at two temperatures to determine mixing enthalpies for liquid Al-Cu-Li alloys. At 986 K, Cu was dropped into an Al-Li bath with XAl/XLi=4 to form liquid alloys with 0.02≤XCu≤0.285, and, at 945 K, Li was dropped into an Al-Cu bath to form alloys with 0.023≤XLi≤0.265. The experimental emf and calorimetric results were combined with available data from the literature to make a new evaluation and to calculate the Al-Cu-Li phase diagram. Good conformity between emf and calorimetric results from the present studies and the optimized thermodynamic parameters was observed for XAl/XCu=9 and 4; however, for XAI/XCu=7/3, differences were observed in the one-, two-, and three-phase boundaries when compared with existing and calculated phase equilibria of the AI-Cu-Li system.