DESCRIPTION OF THE CU-AS-SE TERNARY-SYSTEM

The phase diagram of the Cu-As-Se ternary system was studied by differ ential thermal analysis, X-ray diffraction and metallography analysis. Two ternary phases are observed: the Cu3AsSe4 compound, which melts c ongruently, and the CuAsSe2 compound, which undergoes a peritectic dec omposition. The ternary system is subdivided into 12 secondary triangl es. The 12 ternary invariants are localized: six eutectics, one of whi ch is degenerated at the selenium apex, and six peritectics. Two terna ry liquid-liquid miscibility gaps originating from the Cu-Se binary sy stem are identified. One of these is crossed by a eutectic valley givi ng a first-class ternary monotectic equilibrium. A large vitreous regi on, which comes from the AsSe binary glass zone, is identified; it ove rlaps the liquid-liquid miscibiiity area, giving phase-separated glass es.