Thermodynamic Modeling of the Au-Ge-X (X = In, Sb, Si, Zn) Ternary Systems

TL;DR

This paper models the thermodynamics of Au-Ge-X (X = In, Sb, Si, Zn) systems to support the development of high-temperature Pb-free solders.

Contribution

The study provides new thermodynamic modeling of Au-Ge-X systems using the CALPHAD approach and experimental data.

Findings

The CALPHAD approach was used to model thermodynamics of Au-Ge-X systems.

Liquidus projections and isothermal sections align with experimental findings.

The work supports the creation of a database for Au-Ge-based alloys.

Abstract

In this study, the CALPHAD approach was employed to model the thermodynamics of the Au-Ge-X (X = In, Sb, Si, Zn) ternary systems, leveraging experimental phase equilibria data and previous assessments of related binary subsystems. The solution phases were modeled as substitutional solutions, and their excess Gibbs energies were expressed using the Redlich–Kister polynomial. Owing to the unavailability of experimental data, the solubility of the third elements in the Au-In, Au-Sb, and Au-Zn binary intermetallic compounds was excluded from consideration. Additionally, stable ternary intermetallic compounds were not reported in the literature and, thus, were not taken into account in the present thermodynamic calculations. Calculations of liquidus projections, isothermal sections, and vertical sections for these ternary systems have been performed, aligning with existing experimental findings. These thermodynamic parameters form a vital basis for creating a comprehensive thermodynamic database for Au-Ge-based alloys, which is essential for the design and development of new high-temperature Pb-free solders.

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