The equilibrium diagram of the system gold-indium

Abstract

The equilibrium diagram of the system Au-In has been examined in great detail by a combination of thermal, microscopical, and X-ray techniques. The results are discussed in connexion with the general theory of the alloys of Cu, Ag, and Au with the B sub-group elements. On the gold-rich side of the diagram, the α solid solution in gold is succeeded by an α 1 hexagonal phase with random ABAC... stacking, and this in turn is succeeded by a normal ﻉ close-packed hexagonal phase with ABAB ... stacking, which is followed by ordered hexagonal phases. There is then a typical ˠ phase with the ˠ brass structure, and a newly discovered ψ phase which is remarkable for the very slight maximum in the liquidus curve. In terms of electron concentration limits, the ﻉ Au-In phase differs from the ﻉ Au-Sn and ﻉ Au-Sb phases, but resembles that of the Au-Cd ﻉ phase (previously called α 2 ). There is, however, a remarkable difference between the Au-Cd and A u-In ﻉ phases, in that in the latter there is a clear division between the phases with ABC ABC..., ABAC..., and . stacking, whereas in AuCd alloys heavily faulted structures are found.