Фазовая диаграмма системы C-Hf

К оглавлению: Другие диаграммы (Others phase diargams)


C-Hf (Carbon-Hafnium) H. Okamoto Only one intermetallic phase (NaCl-type CHf) exists in the C-Hf system. Many contradictory phase diagrams and scattered lattice parameter values have been reported, partly caused by considerable Zr impurity retained in raw Hf. The assessed phase diagram is based primarily on the experimental data of [65Rud] and [69Rud]. The boundaries of (bHf) and (aHf) in the assessed diagram are most uncertain. The diagram of [74Ere] was similar to that of [65Rud]. [67Dea] indicated that the (bHf) = (aHf) transition was a peritectoid occurring at 1890 C and that ( bHf) extends to 9 at.% C. [Shunk] also drew a similar diagram, based on [62Kat] and [64Sar]. The sublimation point of C (graphite) is 3826 C [Melt]. The eutectic composition of (C) was reported as 32 с 1.5 at.% Hf and 3180 с 20 C [65Rud]. The composition of the congruent melting of CHf is off-stoichiometric at 52.5 at.% Hf [65Sar] or 51.5 с 0.3 at.% Hf [65Rud]. The assessed maximum homogeneity range of CHf is 50.5 to 66 at.% Hf [69Rud]. [63Ada2] determined that there are no polymorphs in CHf, at least up to 2800 C, and there is no indication of polymorphs above this temperature, either. The reactions involving L, CHf, (bHf), and (aHf) were very controversial, partly because the existence of the allotropic transformation of Hf was unknown in earlier experiments and both Zr and O impurities significantly affect the reaction temperatures and possibly the reaction types. A L + CHf = (aHf) peritectic was proposed at 2350 с 45 C [65Rud]. The L = (bHf) + (aHf) eutectic temperature is 2218 с 10 C [65Rud]. The (bHf) solvus is not well defined. The maximum C solubility in (bHf) is about 1 at.% [ 65Rud]. The solid solubility of C in (aHf) at 1550 C is much less than 10 at.% , because a sintered alloy of this composition contained CHf [60Ben]. The maximum solubility is 14 с 3 at.% at 2360 C [65Rud]. Lattice parameters of alloys quenched from 1930 C indicated that the (bHf) solvus is located at 5 at.% C [67Dea]. However, the lattice parameters were those of (aHf). Apparently, the high-temperature phase could not be retained. Further clarification of the phase relationships near pure Hf is needed. 60Ben: F. Benesovsky and E. Rudy, Planseeber. Pulvermetall., 8(2), 66-71 (1960) in German. 62Ava: R.G. Avarde, A.I. Avgustinik, Yu.N. Vil'k, Yu.D. Kondrashov, S.S. Nikol'skii, Yu.A. Omel'chenko, and S.S. Ordan'yan, Zh. Prikl. Khim., 35, 1976- 1980 (1962) in Russian; TR: J. Appl. Chem., USSR, 35, 1899-1902 (1962). 62Bit: H. Bittner and H. Goretzki, Monatsh. Chem., 93, 1000-1004 (1962) in German. 62Kat: H. Kato and M. Copeland, U.S. At. Energy Comm., USBM-U-921, 12-13 (1962) ; U.S. At. Energy Comm., USBM-U-952, 14-16 (1962); U.S. At. Energy Comm., USBM- U-978, 5-7 (1962); U.S. At. Energy Comm., USBM-U-1001, 7-8 (1962); U.S. At. Energy Comm., USBM-U-1031, 19-21 (1963); U.S. At. Energy Comm., USBM-U-1057, 14-19 (1963); quoted in [Shunk]. 62Zhe: V.I. Zhelankin, V.S. Kutsev, and B.F. Ormont, Zh. Neorg. Khim., 7(8), 1762-1764 (1962) in Russian; TR: Russ. J. Inorg. Chem., 7(8), 912-913 (1962). 63Ada1: R.P. Adams and R.A. Beall, U.S. Bur. Mines, Rep. Invest. 6304, 17 pp ( 1963). 63Ada2: R.P. Adams and A.G. Pike, U.S. At. Energy Comm., USBM-U-1091, 5-6 ( 1963); quoted in [Shunk]. 63Kri: N.H. Krikorian, T.C. Wallace, and J.L. Anderson, J. Electrochem. Soc., 110(6), 587-589 (1963). 63Rud: E. Rudy and F. Benesovsky, Monatsh. Chem., 94(1), 204-224 (1963) in German. 63Zhe: V.I. Zhelankin and V.S. Kutsov, Zh. Strukt. Khim., 4(6), 865-867 (1963) in Russian; TR: J. Struct. Chem. (USSR), 4(6), 796-798 (1963). 64Hou: C.R. Houska, J. Am. Ceram. Soc., 47(6), 310-311 (1964). 64Sar: R.V. Sara and C.E. Lowell, Tech. Rep. WADD-TDR-60-143, pt. V (AD 608301) , 19-44 (1964); quoted in [Shunk]. 65Rud: E. Rudy, Tech. Rep. AFML-TR-65-2, Part 1, 4 (AD 472697), Air Force Materials Lab., Air Force Systems Command, Wright-Patterson Air Force Base, OH, 62 pp (1965). 65Sar: R.V. Sara, Trans. AIME, 233(9), 1683-1891 (1965). 66Ord: S.S. Ordanyan, A.A. Kraskovskaya, and A.I. Avgustinik, Izv. Akad. Nauk SSSR, Neorg. Mater., 2, 299-302 (1966) in Russian; TR: Inorg. Mater., USSR, 2, 256-259 (1966). 67Dea: D.K. Deardorff, M.I. Copeland, and R.P. Adams, U.S. Bur. Mines, Rep. Invest., No. 6983, 16 pp (1967). 68Ram: L. Ramqvist, Jernkontorets Ann., 152, 517-523 (1968). 69Rud: E. Rudy, AFML-TR-65-2, Part V, Air Force Materials Lab., Air Force Systems Command, Wright-Patterson Air Force Base, OH, 689 pp (1969). 71Zai: Yu.G. Zainulin, S.I. Alyamovskii, G.P. Shveikin, and P.V. Gel'd, Teplofiz. Vys. Temp., 9(3), 546-549 (1971) in Russian; TR: High Temp., 9(3), 496-499 (1971). 74Ere: V.N. Eremenko, T.Ya. Velikanova, and S.V. Shabanova, Strukt. Faz. Fazovye Prevrashch., Diagr. Sostoyaniya, O.S. Ivanov and Z.M. Alekseeva, Ed., Nauka, Moscow, 129-132 (1974) in Russian. 78Mas: V.M. Maslov, A.S. Neganov, I.P. Borovinskaya, and A.G. Merzhanov, Fiz. Goreniya Vzryva, 14(6), 73-82 (1978) in Russian; TR: Combustion Explosion Shock Waves, 14(6), 759-767 (1979). Published in Bull. Alloy Phase Diagrams, 11(4), Aug 1990. Complete evaluation contains 2 figures, 4 tables, and 66 references. 1