Surface tension, density, and molar volume of liquid Sb-Sn alloys: Experiment versus modeling

Abstract

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 mm 2 ) 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. In the last decade binary and multicomponent Sn alloys, with alloying elements such as Ag, Bi, Sb, In, Cu, and Zn, have been investigated to find a substitute for toxic Pb-Sn solders. Experiments have focused on thermodynamic, physical, and mechanical properties, and calculations of the phase diagrams and solidification paths from the optimized thermodynamic parameters. Among physical properties, surface tension and interfacial tension measurements are very important for practical application because they are directly correlated with the wettability of a substrate by the solder. When the addition of another component to binary or higher order liquid alloys decreases the surface tension and interfacial tension, it simultaneously improves wettability. Hence, measurements of the surface tension can be useful for predicting the effect of modifying elements on solder properties. Our previous studies [2002Mos1, 2002Mos2] have shown that the surface tension obtained by the maximum bubble method is higher than the interfacial tension by the meniscographic method due to an interfacial tension contribution to the measurement at the sample-flux interface. The multicomponent alloys with antimony are possible substitutes for Pb-Sn solders due to the improvement of wetting properties, strength, thermal fatigue resistance, and creep strength. Therefore, surface tension and density measurements were performed in this study for liquid Sb-Sn alloys over the entire range of concentration and a broad temperature range period. This investigation is considered to be a first step toward investigations of the Sn-rich AgSb-Sn system. The surface tensions calculated by Butler’s model are discussed and compared with those from the present measurements. An additional reason for the present investigation was to check whether the addition of Sb to Sn in liquid alloys actually decreases the surface tension as noted in [1999Jan] and [1997Lee]. In contrast, a recent paper [2002Kim] has reported that the wettability of Sb-Sn decreases with Sb additions.