Isoplethal Sections of the Liquidus Projection and the 250°C Phase Equilibria of the Sn–Ag–Cu–Ni Quaternary System at the Sn-Rich Corner

Abstract

Isoplethal sections of the 250°C phase equilibria at 95 at%Sn and 97 at%Sn and that of the liquidus projection at 97 at%Sn of the Sn–Ag–Cu–Ni system were determined. Sn–Ag–Cu–Ni quaternary alloys at constant Sn contents were prepared. The alloys for the isothermal phase relationship determination were equilibrated at 250°C for various lengths of time, and then the equilibrium phases in the annealed alloys were analyzed. The alloys for the liquidus projection determination were melted at 1000°C, and were solidified in the furnace at a cooling rate approximately 10°C/min. The solidified alloys were metallographically examined and the primary solidification phases were determined. The isoplethal sections of the 250°C phase equilibria and the liquidus projection were constructed based on the quaternary experimental data and the 250°C isothermal sections and the liquidus projection of the constituent ternary systems, respectively. Neither ternary nor quaternary intermetallic compounds were found. Most of the binary compounds have significant ternary solubilities, but only very limited quaternary solubilities. Four different primary solidification phases are found of the Sn–Ag–Cu–Ni alloys with 97 at%Sn, and the compositional regime of the primary Ni₃Sn₂ phase is relatively much smaller.