Effect of Cu and Sn on liquid–liquid interfacial energy in ternary and quaternary Al–Bi-based monotectic alloys

The influence of Cu and Sn on the interfacial energy between Al-rich and Bi-rich liquids has been studied. The liquid–liquid interfacial tension is increased when Cu is added to the Al34.5Bi65.5 (numbers indicate wt.%) binary and it is decreased when Sn is added. Simultaneous addition of Cu and Sn in equal quantity to the binary Al–Bi alloy results in a decrease of the interfacial tension at low temperature and in its increase at high temperature. Temperature dependences of the interfacial tension in the alloys studied are well described by the function σαβ = σ0 (1 − T/TC)μ with a constant σ0 and the critical-point exponent μ = 1.3.