| Abstract Scope |
Sn-Cu and Sn-Bi are important Pb-free solders, and the Bi-Sn-Cu ternary system is crucial for the electronic industry. Its liquidus projection is experimentally determined in this study. The primary solidification phases are identified based on the microstructures of the quenched alloys. There are seven primary solidification phases: (Cu), β, γ-CuSn, ε-Cu3Sn, η-Cu6Sn5, (Sn) and (Bi), and no ternary compound is found. Although there are no liquid miscibility gaps in its three binary constituent systems, there is a liquid miscibility gap with a large compositional homogeneity range in this ternary system. When the alloys solidify through the miscibility gap, interesting microstructures consisting of two regions with very different compositions are observed. The boundaries of the miscibility gap are determined accordingly. There are eight invariant reactions, including three reactions intersecting with the liquid miscibility gaps. The invariant reaction temperatures are also determined using DTA; for example, it is 760℃ for L_I+(Cu)=β+L_II. |