Phase transformation temperatures of the Sn–In–Ni–Zn quaternary system

The Sn–In–Ni–Zn system is an important material system for electronic soldering. Various alloys, such as Sn–In, Sn–Ni, Sn–Zn, and Sn–In–Zn, are frequently used in electronic products. Unexpectedly, it was found that even for these important systems, there are only limited experimental measurements of the liquidus and invariant reaction temperatures. Additionally, there are significant differences between the experimental results and those calculated using the CALPHAD method with various available databases. To tackle these issues, Sn-rich alloys including Sn–Zn, Sn–In, Sn–Ni, Sn–In–Zn, Sn–Ni–Zn, Sn–In–Ni, and Sn–In–Ni–Zn were prepared. Their liquidus temperatures were determined experimentally through thermal analysis combined with holding-quenching experiments, while invariant reaction temperatures were measured using thermal analysis with an internal marker. The uncertainties in the measurements are 3 °C for the liquidus temperatures and 1 °C for the invariant reactions. Although high-quality thermal analysis can determine phase transformation temperatures with an accuracy of up to 1 °C, reliable determination of liquidus temperatures becomes quite challenging when the heat effect is not significant. This may explain why the literature data are inconsistent. These experimental results were subsequently used to refine CALPHAD-type modeling, and phase diagram calculations with better agreement were achieved.