Фазовая диаграмма системы Cu-S

К оглавлению: Другие диаграммы (Others phase diargams)


Cu-S (Copper-Sulfur) D.J. Chakrabarti and D.E. Laughlin Numerous studies have been conducted on the Cu-S system. Uncertainty, however, persists regarding the phase equilibria, because of the strong tendency of the system to form several metastable phases. Marked thermomechanical history dependence is exhibited by many of these phases. For example, extreme sensitivity to applied pressure has been known to cause a phase transformation during specimen preparation by grinding. However, the following features have been well established. The liquid, L, manifests two miscibility gaps between the liquids L1 and L2 above 1105 C at Cu-rich compositions and between the liquids L2 and L3 above 813 C at higher S compositions. The fcc terminal solid solution, (Cu), exhibits restricted solubility of S, amounting to 0.023 at.% at 1067 C. The solubility of S decreases with increasing purity of Cu. The orthorhombic terminal solid solution, (S), is stable up to ~115 C, with negligible solubility of Cu. The monoclinic low-chalcocite (aCh), is stable up to 103.5 с 0.5 C at the stoichiometric composition of Cu2S and up to 90 с 2 C at 33.41 at.% S. The hexagonal high-chalcocite (bCh) is stable from 103.5 с 0.5 C at the Cu-rich limit of stoichiometric Cu2S and from 90 с 2 C at 33.44 at.% S up to 435 C at 33.34 at.% S. The fcc digenite (Dg) has a broad phase field, with the Cu-rich boundary approximately at Cu2S stoichiometry between 435 and 1130 с 2 C. The Cu- deficient boundary extends to form the defect compound Cu2-dS, which is stable up to 507 с 2 C at 36.60 at.% S and down to 72 с 3 C at 35.65 at.% S. The orthorhombic djurleite (Dj) has the nominal composition Cu1.96S and is stable up to 72 с 3 C at Cu1.934S and up to 93 с 2 C at 33.99 at.% S. The orthorhombic compound anilite (An) of stoichiometry Cu1.75S (36.36 at.% S) is stable up to 75 с 3 C. The hexagonal compound covellite (Cv) of stoichiometry CuS is stable up to 507 с 2 C. The assessed Cu-S phase diagram is based primarily on the work of [77Pot]. Data on much of the solidus and liquidus are derived from [72Coo]. Data on the Dg and Ch boundaries are based on the studies of [66Ros] and [72Coo]. Additionally, the work of [47Jen], [57Ruh], [58Dju], [59Oud], [60Joh], [69Mor], [70Mor], [74Rau], and [80Sha] were reviewed. 47Jen: E. Jensen, Avhandl. Norske Videnskaps-Akad. Oslo, I. Mat.-Naturw. Kl., 6, 1-14 (1947). 57Ruh: W. Ruhl and E. Saur, Ber. Oberhess, Ges. Naturw. Heilk. Giessen, Naturw. Abt., 28, 35-47 (1957) in German. 58Dju: S. Djurle, Acta Chem. Scand., 12, 1415-1426 (1958). 59Oud: J. Oudar, Compt. Rend., 249, 259-261 (1959) in French. 60Joh: F. Johannsen and H. Vollmer, Z. Erzbergbau MettalhЃttenwes., 13, 313- 322 (1960) in German. 66Ros: E.H. Roseboom, Jr., Econ. Geol., 61, 641-672 (1966). 69Mor: N. Morimoto, Am. Miner., 54, 1256-1268 (1969). 70Mor: N. Morimoto and K. Koto, Am. Miner., 55, (1-2), 106-117 (1970). 72Coo: W.R. Cook, Jr., Nat. Bur. Stand. Spec. Pub. 364, 703-712 (1972); Ph.D. thesis, Case Western Reserve University, Cleveland, OH; Gould Labs Univ. Microfilm Order No. 72-27 (1971). 74Rau: H. Rau, J. Phys. Chem. Solids, 35, 1415-1424 (1974). 77Pot: R.W. Potter, II, Econ. Geol., 72(8), 1524-1542 (1977). 80Sha: R.C. Sharma and Y.A. Chang, Metall. Trans. B, 11, 575-583 (1980). Published in Bull. Alloy Phase Diagrams, 4(3), Nov 1983. Complete evaluation contains 10 figures, 24 tables, and 116 references. Special Points of the Cu-S System Reaction Composition, at.% S(Cu/S) Temperature, Reaction type