Microstructural analysis and thermal conductivity of the Ag–Bi–Sn alloys

Abstract

Structural and thermal properties of five Ag–Bi–Sn ternary alloys with tin content ranging from 12.8 to 75.1 mass% and nearly equal mass contents of silver and bismuth were investigated in this study. Microstructures and melting properties of as-solidified alloy samples were examined using scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD) analysis, and differential thermal analysis (DTA) in combination with the CALPHAD (CALculation of PHase Diagram) method. The observed microconstituents were Ag3Sn, (Sn) and, (Bi) phases as well as ternary (Sn)+(Bi)+Ag3Sn eutectic. The measured temperature of the ternary eutectic reaction was 138.0°C.The flash method was used for thermal diffusivity measurements in the temperature range from 25 to 100°C. Based on the measured values of thermal diffusivity, thermal conductivity of the solid Ag–Bi–Sn alloys was obtained. Thermal conductivity of the studied Ag–Bi–Sn ternary alloys considerably increases with increasing tin concentration and slightly decreases with increasing temperature.