Thermodynamic modeling of the Au–Ge–Sn ternary system

Abstract

a b s t r a c tBased on the available experimental information, the Au-Ge binary system has been thermodynamically assessed using the CALPHAD method. The solution phases including liquid, fcc A1, hcp A3, diamond A4, bct A5 and D024, were modeled as substitutional solutions, of which the excess Gibbs energies were expressed by the Redlich-Kister polynomial. The solubility of Ge in Au 5 Sn, AuSn, AuSn 2 and AuSn 4 was not taken into account due to the lack of experimental data. Combined with previous assessments of the Au-Sn and Ge-Sn binary systems, the thermodynamic description of the Au-Ge-Sn ternary system has been performed to reproduce the reported phase equilibria. The liquidus projection and several vertical sections of this ternary system have been calculated, which are in reasonable agreement with the reported experimental data.

Thermodynamic description of the Au–Ge–Sb ternary system

“…(j) L Au,Ge and (j) L Au,Sb are binary interaction parameters, which are taken directly from the Au-Ge and Au-Sb systems assessed by Wang et al [13] and Liu et al [14], respectively. The ternary interactive parameter L Au,Ge,Sb is formulated with Redlich-Kister-Muggianu expression as follows:…”

“…Among the three binary systems, the Au-Ge and Au-Sb binary systems have been well assessed thermodynamically by Wang et al [13] and Liu et al [14], respectively. The calculated phase diagrams of the Au-Ge and Au-Sb binary systems are shown in Figs.…”

“…1 and 2, respectively. Thermodynamic parameters for the Gibbs energies of various phases in the Au-Ge and Au-Sb binary systems obtained by Wang et al [13] and Liu et al [14] are directly adopted during the present optimization and calculation. The Ge-Sb binary system was reviewed previously by Olesinki et al [15] and was optimized later by Chevalier [16], which can reproduce most experimental information on thermodynamic properties and phase boundaries.…”

Wetting and Soldering Behavior of Eutectic Au-Ge Alloy on Cu and Ni Substrates

“…5 The addition of metals, such as Si, Sn, Sb or In, to the eutectic alloy leads to a further decrease in the melting point. [6][7][8] Therefore, despite their high cost, Au-Ge-based alloys have been proposed as possible high-temperature leadfree solder materials for highly loaded components such as high-power microelectromechanical systems (MEMS) devices but also in space technology as well as for corrosion-resistant solders for components exposed to aggressive media such as for sensors in corrosive atmospheres and biomedical devices. [9][10][11] The soldering process consists in the formation of a joint between the molten solder and a solid metal substrate.…”

Thermodynamic assessment of the Cu–Ge binary system

“…Reliable thermodynamic information on the relative stabilities of TM-germanides is essential to control the interfacial microstructure evolution and thus to design optimal processing. On the other hand, Au-based alloys containing Ge are of interest for novel high temperature lead-free solder alloys [6][7][8][9]. For example, the Au-Ge binary system is characterised by a deep eutectic reaction with its temperature of around 360 • C, making it interesting for high temperature Au-based solders.…”