Exsolution in the Au–Au3Cu Region and Correction of the Au–Ag–Cu Phase Diagram

Abstract

The phase composition of native gold was examined in an insufficiently studied part of the Au–Ag–Cu system in the range between pure gold and Au3Cu. In this region, a miscibility gap has been established for the Au–Ag–Cu solid solution, which is decomposed into Au–Ag–Cu and Au3Cu phases. These results in combinations with previously obtained and literature data made it possible to construct a complete phase diagram of the Au–Ag–Cu system in the gold-rich region for low (about 100°C) temperature. The diagram demonstrates the field of a homogeneous Au–Ag–Cu solid solution, and two-phase fields (Au3Cu and Au–Ag–Cu solid solution) and (AuCu and Au–Ag–Cu solid solution), which are separated by a three-phase field (Au3Cu, AuCu, and Au–Ag–Cu solid solution).