Фазовая диаграмма системы Cr-S

К оглавлению: Другие диаграммы (Others phase diargams)

Cr-S (Chromium-Sulfur) M. Venkatraman and J.P. Neumann The assessed Cr-S phase diagram is based primarily on the experimental data of [38Vog], [57Jel], [69Pop], and [77Rau]. The system is characterized by two miscibility gaps in the liquid state that separate the metal-rich, the sulfide- rich, and the sulfur-rich liquids and the occurrence of several intermediate phases in the solid state between approximately 50 to 60 at.% S. The phase relations in this region are very complex and not completely resolved. The existence of the following chromium sulfide phases has been clearly established: Cr1.03S (monoclinic), CrS (hexagonal), Cr7S8 (hexagonal), Cr5S6 ( hexagonal), Cr3S4 (monoclinic), Cr2S3(I) (hexagonal), and Cr2S3(II) ( rhombohedral). Two sulfides containing >60 at.% S have been reported-Cr5S8 (61.5 at.% S) [ 69Sle] and Cr2S5 (71.4 at.% S) [67Noe]. Cr5S8 was prepared at 1200 C under a pressure of 89 kbar; it is not known if the phase is stable also at atmospheric pressure. Cr3S5 was observed during the thermal decomposition of a Cr alloy containing 75 at.% S. Depending on the external pressure, it decomposes between 70 to 300 C [67Noe]. The phase equilibria involving the liquid state are based on the work of [ 38Vog]. The liquid miscibility gap between the metal-rich liquid L1 and the sulfide-rich liquid L2 extends at the monotectic temperature 1550 C from 3.5 to 38.0 at.% S. The selected melting temperature of CrS, 1565 с 15 C, is taken from [38Vog]. The solid-state phase relations above ~700 C are based mainly on the detailed sulfur pressure measurements of [77Rau]; those below ~700 C are based primarily on the X-ray studies of [57Jel] and [69Pop]. Following [79Cha], a single, continuous phase field is shown for the sulfide CrS; its homogeneity range extends from ~50 to ~59 at.% S at ~1300 C. Based on the stability diagram, a peritectoid decomposition of Cr3S4 at 1152 C is suggested. The temperatures of the invariant three-phase equilibria involving the intermediate phases Cr1.03S, CrS, Cr7S8, and Cr5S6 are taken from [69Pop]; those involving the phases Cr2S3(I) and Cr2S3(II) are speculative. According to [57Jel], the solubility of S in (Cr) is very small. This was confirmed by [76Bar] and [76Gro], who obtained a value 1.9 x 10-3 at.% S at 1200 C. Because of the importance of the sulfidation behavior of Cr and Cr alloys in the coal and oil industries, numerous investigations have been devoted to this subject. In general, sulfide scale grows by an outward diffusion of Cr atoms over vacant metal sites [71Str]. [36Har] reported spontaneous magnetism in the Cr-S system at ~54 at.% S. The very complex behavior of the sulfides depends strongly on their defect structure. The high-temperature CrS phase is paramagnetic and exhibits metallic conductivity. Cr1.03S is paramagnetic above the N‚el temperature of 455 с 5 K and is antiferromagnetic below it. A magnetic anomaly is present in the temperature range 240 to 300 K. This phase is a semiconductor. Cr7S8 is paramagnetic above the N‚el temperature of 130 с 5 K and is antiferromagnetic below it. This phase is a metallic conductor. Cr5S6 is paramagnetic above the Curie temperature of 305 с 5 K, ferrimagnetic between the Curie temperature and the N‚el temperature of 160 с 10 K, and antiferromagnetic below the N‚el temperature. The N‚el temperature has a hysteresis of ~10 K. This phase is a metallic conductor. Cr3S4 is paramagnetic above the N‚el temperature of 215 с 10 K, and is antiferromagnetic below it. This phase is a metallic conductor. Cr2S3(I) is paramagnetic above the Curie temperature of 115 с 10 K and is ferrimagnetic below it. This phase is a metallic conductor. Cr2S3(II) is paramagnetic above the N‚el temperature of 117 с 5 K; it exhibits a mixed ferrimagnetic-antiferromagnetic behavior below the N‚el temperature. It is a semiconductor. Cr5S8, and Cr2S5 are paramagnetic at room temperature. 27Jon: W.F. de Jong and H.W.V. Willems, Physica, 7, 74-79 (1927) in Dutch. 36Har: H. Haraldsen and A. Neuber, Naturwissenschaften, 24, 280 (1936) in German. 37Har: H. Haraldsen, Z. Anorg. Allg. Chem., 234, 372-390 (1937) in German. 38Vog: R. Vogel and R. Reinbach, Arch. EisenhЃttenwes., 11, 457-462 (1938) in German. 57Jel: F. Jellinek, Acta Crystallogr., 10, 620-628 (1957). 57Yuz: M. Yuzuri, T. Hirone, H. Watanabe, S. Nagasaki, and S. Maeda, J. Phys. Soc. Jpn., 12(4), 385-389 (1957). 58Jel: F. Jellinek, Mem. Sect. Chim. Miner. Congr. Int. Chim., 187-192 (1958). 60Kam1: T. Kamigaichi, J. Sci. Hiroshima Univ. A, 24(2), 371-388 (1960). 60Kam2: T. Kamigaichi, K. Masumoto, and T. Hirara, J. Phys. Soc. Jpn., 15, 1355 (1960). 64Yuz: M. Yuzuri and Y. Nakamura, J. Phys. Soc. Jpn., 19(8), 1350-1354 (1964). 66Bou: R.J. Bouchard and A. Wold, J. Phys. Chem. Solids, 27, 591-595 (1966). 67Noe: A. Noel, J. Tudo, and G. Tridot, Compt. Rend. Paris, Ser. C, 264, 443- 445 (1967) in French. 69Fil: V.S. Filatkina, L.M. Doronina, and S.S. Batsanov, J. Struct. Chem., 10, 253-258 (1969). 69Pop: T.J.A. Popma and C.F. van Bruggen, J. Inorg. Nucl. Chem., 31, 73-80 ( 1969). 69Sle: A.W. Sleight and T.A. Bither, Inorg. Chem., 8(3), 566-569 (1969). 70Lov: C. Lovasz and H.D. Lutz, Z. Naturforsch. B, 25, 313-314 (1970) in German. 71Erd: E. Erd”s, P. Brezina, and R. Scheidegger, Werkst. Korros., 22, 148-157 ( 1971) in German. 71Iga: K. Igaki, N. Ohashi, and M. Mikami, J. Phys. Soc. Jpn., 31(5), 1424- 1430 (1971). 71Str: K.N. Strafford and A.F. Hampton, J. Less-Common Met., 25, 435-439 (1971) . 73Bab: D. Babot and M. Chevreton, J. Solid State Chem., 8, 166-174 (1973) in French. 73Lut: H.D. Lutz and K.H. Bertram, Z. Anorg. Allg. Chem., 401, 185-188 (1973) in German. 75Anz: S. Anzai and Y. Hamaguchi, J. Phys. Soc. Jpn., 38(2), 400-403 (1975). 75Kat: A. Katori, S. Anzai, and T. Yoshida, J. Inorg. Nucl. Chem., 37, 323-324 (1975). 76Bar: N. Barbouth and J. Oudar, Scr. Metall., 10, 415-419 (1976) in French. 76Gro: R. Groliere and N. Barbouth, Mem. Sci. Rev. Metall., 73, 71-76 (1976) in French. 77Rau: H. Rau, J. Less-Common Met., 55, 205-211 (1977). 79Cha: Y.A. Chang, J.P. Neumann, and U.V. Choudary, Phase Diagrams and Thermodynamic Properties of Ternary Copper-Sulfur-Metal Systems, INCRA Monograph VII, International Copper Research Association, New York, 53-57 ( 1979). 81Taz: Y. Tazuke, J. Phys. Soc. Jpn., 50(2), 413-420 (1981). 82Shv: L.A. Shvartsman, E.F. Petrova, A.N. Tsvigutnov, and L.I. Chernomorchenko, Russ. Metall., 5, 151-154 (1982). Submitted to the APD Program. Complete evaluation contains 3 figures, 8 tables, and 99 references. Special Points of the Cr-S System