Effect of Ag addition to Zn-12Al alloy on kinetics of growth of intermediate phases on Cu substrate

Zn-Al-Ag solders based on eutectic Zn-12Al alloy containing 0.5-1.5 at.% Ag are developed for ultra high temperature applications. Wettability tests carried out on Ag-doped Zn-Al alloys on Cu substrates showed the formation of Cu-Zn phases at the interface. Wettability studies were performed with the use of flux at 500 °C for 15, 30, 60, 180, 240, 900, 1800 and 3600 s, and for 240 s at 460, 480, 520, 550 °C, respectively. Experiment was designed this way in order to demonstrate the effect of Ag addition on the kinetics of formation and growth of CuZn, Cu5Zn8, CuZn4 phases, which were identified with EDS analysis. In addition to improving spreadability of Zn-Al-Ag alloys, Ag increases their melting temperature, electrical resistivity, and coefficient of thermal expansion.