Description of the Liquidus Surface and Characterization of Alloys of the Ternary Bi-Cu-In System

Abstract

Lead-free solders with copper are considered as a possible substitution for standard lead-tin solders. Ternary Bi-Cu-In system is a potential soldering material based on copper. For a more complete characterization of the ternary Bi-Cu-In system, alloys from the three vertical sections were investigated using microstructural analysis as well as by electrical conductivity and Brinell hardness measurements. The microstructures of the alloys were investigated at room temperature by application of scanning electron microscopy combined with energy dispersive spectrometry and optical microscopy. Isolines of electrical conductivity and hardness for the entire Bi-Cu-In system were calculated using regression models. In addition, a thermodynamic assessment of the system has been carried out by calculation of the isothermal section at 25 °C and description of the liquidus surface using the CALPHAD method. Experimental and analytical results were found to be in a good agreement.