Thermochemistry of the quaternary system Ag-Cu-Ni-Sn

The quaternary intermetallic system Ag-Cu-Ni-Sn and its binary and ternary constituents are of importance because Ag-Cu-Sn is a key systems for lead-free soldering and Ni is a frequently used contact material. The aim is to establish reliable thermochemical and phase relation data from literature and our own experiments. First we determined partial and finally integral enthalpies of mixing of liquid alloys by calorimetric measurements performed at different temperatures. The experimental results were fitted using the Redlich-Kister-Muggiano formula in order to provide a numerical description of the integral enthalpies of mixing according to the CALPHAD method. The experimental results were also compared with extrapolations and theoretical values from pseudo-potential calculations. Our work is considered as a contribution to the COST-Action 531 "Lead-free solder materials". The main objective of the action is to increase the basic knowledge on possible alloy systems that can be used as lead-free solder materials and to provide a scientific database on possible lead-free solder materials and soldering processes. Experimental thermochemical data are important for the optimization of phase diagram calculations as well as the evaluation of physicochemical properties like e.g., diffusion and surface tension.