Au-lnert Gases Ag-lr The crystal structures and lattice parameters of the pure elements are given in Table 2. Cited References 68Gul: B.B. Gulyaev and G.F. Dvorshkaya, "Generalization of the Phase Diagram of Binary Copper-, Silver-, and Gold-Base Alloys," in Phase Diagrams of Metallic Systems, E.M. Savit- skii, Ed., Akad. Nauk SSSR, 267-273 (1968) in Russian. (Equi Diagram; Theory) 81Kir: R.E. Kirk and D.F. Othmer, Encyclopedia of Chemical Technology, Vol. 12, 3rd ed., Interscience Publishers, New York, 254 (1981). (Equi Diagram; Compilation) Au-inert gases evaluation contributed by H. Okamoto and T.B. Massalski, Department of Metallurgical Engineering and Materials Science, Carnegie- Mellon University, Pittsburgh, PA 15213, USA. Work was supported by the International Gold Corporation Limited (]nterGold) and American Society for Metals (ASM). Literature searched through 1984. Part of the bibliographic search was provided by ASM. Professor Massalski is the ASM/NBS Data Pro- gram Editor-in-Chieffor Binary Alloys and is also Co-CategoryEditor for binary gold alloys with Dr. Okamoto. The Ag-lr (Silver-Iridium) System 107.8682 192.22 By I. Karakaya and W.T. Thompson Royal Military College of Canada Equilibrium Diagram An equilibrium diagram based on experimental data is not available in the literature for the Ag-Ir system. Ir is insoluble in liquid Ag [00Ros]. Measurements of micro- hardness, electrical resistivity, thermo-emf, and mi- crostructure indicate very small solid solubility of Ir in (Ag) and of Ag in (Ir) [59Rud]. The most dilute alloys (0.3 at.% Ir and 1.8 at.% Ag) have been reported to occur in the two-phase region. A change in microhardness of di- lute alloys from the microhardness values for the pure el- ements indicate that the solid solubilities of Ir in (Ag) and of Ag in (Ir) are less than 0.3 at.% Ir and 1.8 at.% Ag, respectively. Metallographic studies of Ag-Ir alloys did not show the presence of any intermediate phases [59Rud]. Differen- tial thermal analysis of Ag-rich alloys indicated that the melting points of the alloys were very close to the melt- ing point of pure Ag. An approximate phase diagram cal- Fig. 1 Assessed Ag-lr Phase Diagram (Approximate) q) o Wei~hL 0 IO 20 30 40 50 2500 ~ ' ' , .... --~ , . . . . i ....... r ..... 1 C+Lo /i L1, 2000- / i n t l i l # l 1500- C + (Ir) Percent Iridium 60 70 80 90 i00 ~ q ............................. L ~ : "'2447~ 98.5 2177~ L, + (Ir) I000 961~ (Ag) (It) - 5oo.-~ 0 Ag 10 30 40 50 60 70 80 90 100 Atomic Percent Iridium Ir I. Karakaya and W.T. Thompson, 1986. Bulletin of Alloy Phase Diagrams Vol. 7 No. 4 1986 359