Thermodynamic investigation of the Ag–Bi–Sn ternary system (original) (raw)
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Thermodynamic Properties of Liquid Ag-Bi-Sn Alloys
Journal of Electronic Materials, 2007
As a promising lead-free solder, the thermodynamic properties of the liquid ternary Ag-Bi-Sn system were investigated. Using an appropriate galvanic cell, the partial free energies of Sn in liquid Ag-Bi-Sn alloys were determined as a function of concentration and temperature. Thermodynamic properties were obtained for 27 alloys. Their composition was situated on three cross sections with the constant ratios of Ag:Bi = 2:1, 1:1, and 1:2. The integral Gibbs free energy and the integral enthalpy for the ternary system at 900 K were calculated by Gibbs-Duhem integration.
Physicochemical properties of liquid Ag–Bi–Sn
Physica B: Condensed Matter, 2007
Free energies of mixing in liquid Ag-Bi-Sn are deduced from EMF measurements. The excess free energy was found to adopt negative values near the Ag-rich corner, whereas positive values are the dominant feature towards the Bi-Sn side of the ternary system. The section with the constant atomic fraction ratio of c Ag =c Bi ¼ 2 marks the tentative borderline between the two regimes. The surface tension and the surface concentrations of the liquid system were calculated with the help of the experimental thermodynamic activity coefficients. The results indicate a preferential segregation of Bi and Sn atoms into the surface layer. Excepting the Ag-rich corner of the system (c Ag 40.9), the surface is only scarcely populated by Ag atoms. Up to composition ratios of c Ag /c Bi E2 the surface concentration of Ag is found to be less than 1 at%. As a consequence, over a wide range of the ternary system, the surface tension is not very different from the value of pure Bi or Sn. The calculated viscosity is indicated to be primarily dependent on the concentration of Ag, whereas the substitution of Bi by Sn at a constant concentration of Ag yields only small changes. Due to their close correlation with the free energy of mixing, the viscosities show positive deviations from ideality for alloys with c Ag /c Bi o2 and negative deviations if c Ag /c Bi 42.
Calculation of the thermodynamic properties of liquid Ag-In-Sb alloys
Journal of the Serbian Chemical Society, 2006
The results of the calculation of the thermodynamic properties for liquid Ga-Sb-Tl alloys at the temperature 1073 K are presented in this paper. Initially, the most appropriate thermodynamic model for the investigated system was selected. Based on a comparison of the values calculated by different geometric models (Kohler, Muggianu, Toop, Hillert, Chou) with the existing experimental based data, asymmetric models of calculation were determined to give the best results. The asymmetric nature of the investigated ternary system was additionally confirmed by the Chou similarity coefficient concept. For these reasons, further complete thermodynamic calculations were performed according to the Hillert model in five sections of the ternary Ga-Sb-Tl system from each corner with the mole ratio of other two components being 9:1; 7:3; 5:5; 3:7 and 1:9. The obtained results include integral excess Gibbs energy dependences on composition for all the investigated sections. The calculated activity values at 1073 K for all components are given in the form of isoactivity diagrams. Comparison between the calculated and experimentally obtained gallium activities shows good agreement.
2017
The surface tensions, viscosities and molar volumes of liquid Ag-Bi-Sn alloys were calculated and presented in this paper. These physical properties have been estimated using the Kohler’s model for surface tension and molar volume and Seetharaman’s model for viscosity. The calculations were done along three selected sections with xSn/xBi = 1/2, 1/1 and 2/1 at different temperatures from 873 to 1273 K. The results show that up to 40 at. % Ag, no influence of the surface tension and no significant dependence on temperature has been noted. With increasing temperature the viscosity decreases smoothly. Both surface tension and viscosity increase significantly at high Ag-concentrations. The molar volume decreases linearly with increasing Ag-compositions and the calculated values are similar to those of additive molar volumes. Received 20 June 2016 Revised 05 Mar 2017 Accepted 09 Mar 2017
Thermodynamics and phase diagram calculation of some sections in the Ag-Bi-Sn system
Journal of the Serbian Chemical Society, 2007
The thermodynamic properties and characteristic phase diagrams of some sections in the Ag-Bi-Sn system were calculated. The thermodynamic functions, such as Gibbs excess energy, activity and enthalpy of formation, were calculated using the RKM model and compared with experimental data reported in the literature. Iso-activity diagrams for all three components at 900 K have been constructed. The calculated phase diagrams of the vertical sections Sn-AgBi, Ag-BiSn and Bi-AgSn, obtained using the ThermoCalc program, were compared and confirmed with the results of DTA measurements from the present work.
Experimental study of the Ag–Sn–In phase diagram
Journal of Alloys and Compounds, 2005
Combined metallographic, differential scanning calorimetry, X-ray and scanning electron microscopy studies have been performed using 27 ternary alloys. The microhardness of the ␣(Ag), (Ag 3 Sn) and (Ag 4 Sn,Ag 3 In) phases has been measured. The ternary extension of the phase (Ag x In y Sn z , where x ≈ 0.36, y ≈ 0.61, z ≈ 0.03) has been revealed in some specimens, although the binary compound (AgIn 2 ) melts at 166 • C. This finding is attributed to the limited cooling rate.
Phase equilibria of the Sn–Ag–Ni ternary system and interfacial reactions at the Sn–Ag/Ni joints
Acta Materialia, 2004
There are no previous phase equilibria studies of the Sn-Ag-Ni ternary system, even though the phase equilibria information is important for the electronic industry. The isothermal section of the Sn-Ag-Ni ternary system at 240°C has been determined in this study both by experimental examination and thermodynamic calculation. Experimental results show no existence of ternary compounds in the Sn-Ag-Ni system, and all the constituent binary compounds have very limited solubilities of the ternary elements. The binary Ni 3 Sn 2 phase is very stable and is in equilibrium with most of the phases, Ag 3 Sn, f-Ag 4 Sn, Ag, Ni 3 Sn 4 and Ni 3 Sn phases. A preliminary thermodynamic model of the ternary system is developed based on the models of the three binary constituent systems without introducing any ternary interaction parameters. This ternary thermodynamic model is used with a commercial software Pandat to calculate the Sn-Ag-Ni 240°C isothermal section. The phase relationships determined by calculation are consistent with those determined experimentally. Besides phase equilibria determination, the interfacial reactions between the Sn-Ag alloys with Ni substrate are investigated at 240, 300 and 400°C, respectively. It is found that the phase formations in the Sn-3.5wt%Ag/Ni couples are very similar to those in the Sn/Ni couples.
Combined Thermodynamic Description and Experimental Investigation of the Ternary Ag–Bi–Ge System
International Journal of Thermophysics, 2019
In this study, the phase diagram of the ternary Ag-Bi-Ge system was thermodynamically assessed and experimentally investigated, which to our knowledge has not been previously done. Differential thermal analysis (DTA), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray powder diffraction (XRD) were applied in order to experimentally assess three vertical sections and two isothermal sections at 200 °C and 400 °C of the Ag-Bi-Ge system. Results of the SEM-EDS and XRD analysis revealed existence of (Ge), (Ag) and (Bi) solid solution phases and absence of any ternary phases. Crystal structures of the identified phases and their corresponding lattice parameters were determined by XRD technique. Phase transition temperatures, including liquidus, solidus and temperature of an invariant reaction, were determined by means of DTA. Thermodynamic calculation of the Ag-Bi-Ge ternary phase diagram was carried out on the basis of optimized thermodynamic parameters for the constitutive binary systems acquired from the literature. Calculated liquidus projection of the Ag-Bi-Ge system and the determined invariant reactions are presented in the study as well. A close mutual agreement between the experimental results and the calculated phase equilibria was obtained.