Effect of Chemical Composition on the Corrosion Resistance, Microstructure, Hardness and Electrical Conductivity Profiles of the Ag-Ge-Sn Alloys

Abstract

This study presents the results of experimental and analytical tests on the corrosion resistance of binary (Ge50Sn50, Ag50Sn50, Ag50Ge50) and ternary (Ag-Ge-Sn) alloys in 3% NaCl, as well as the microstructure, hardness, and electrical properties of the selected ternary Ag-Ge-Sn alloys. Alloys were prepared and analyzed using scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), X-ray powder diffraction (XRD), Brinell hardness testing, and electrical conductivity measurements. Corrosion resistance was evaluated using potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy (EIS), with data fitted using DC Corrosion Technique and Gamry Echem Analyst software. The mechanical properties of the samples are strongly influenced by their phase composition. The study also includes the calculation of the equilibrium phase diagram of the Ag-Ge-Sn system at 25 and 500°C using the Calphad method and the Pandat program. By comparing predicted isothermal sections and experimental results, a good agreement has been reached. Hardness and electrical conductivity values were measured and predicted across the full composition range using an appropriate mathematical model.