Фазовая диаграмма системы H-Y

К оглавлению: Другие диаграммы (Others phase diargams)

H-Y (Hydrogen-Yttrium) D. Khatamian and F.D. Manchester The assessed Y-H phase diagram is based on review of the experimental data of [ 62Lun, 65Yan, 71Lan, 72Fed, 75Bea, 79And, 80Beg, and 82Bon] and was obtained by thermodynamic modeling. Because H is always in the gaseous state and pressure is one of the important thermodynamic variables, a diagram of pressure-composition isotherms was used to construct the assessed equilibrium phase diagram. All of the data points in the assessed equilibrium phase diagram, except those taken from [71Lan], [75Bea], [79And], and [82Bon], were obtained by identifying the limits of the plateau regions of the pressure- composition isotherms. The dashed lines in the assessed equilibrium phase diagram, representing phase boundaries, are drawn through the averages of these data points.The dashed lines in the pressure-composition isotherm diagram were obtained by mapping the phase boundaries. At room temperature, the solid solution phase is located at 20 at.% H. In the assessed diagram, this phase has been designated a. The a phase of the Y-H system retains the cph structure of the a phase for Y metal, the d phase has the fcc structure, and the phase above the approximate composition YH3, labeled e, has the hexagonal structure. [82Bon] and [86Bon] examined the a/a + d phase boundary below 400 C and suggested the existence of an ordered a› phase below about 130 C. The ordering, they suggested, occurs as a pairing of the H atoms. [84Bon] suggested a further transition (unspecified) in the vicinity of -100 C, as determined from dilatometer measurements for samples of concentrations up to YH0.15. Acoustic velocity measurements in YH1.93 [72Bea] and specific heat data for YH2 [62Flo] suggest some phase change in YH2 around 230 K, but the nature of this phase change has not been identified. Below 1000 C, the experimental data points of the assessed diagram are scattered within a narrow region, and the phase boundries can be identified with a reasonable degree of certainty. Above this temperature, the only available data are from [62Lun], and the absence of actual experimental points on their isotherms limits judgment in identifying the phase boundaries. 62Flo: H.E. Flotow, D.W. Osborne, and K. Otto, J. Chem. Phys., 36, 866-872 ( 1962). 62Lun: C.E. Lundin and J.P. Blackledge, J. Electrochem. Soc., 109, 838-842 ( 1962). 64Man: W. Mansmann and W.E. Wallace, J. Phys., 25, 454-459 (1964). 65Yan: L.N. Yannopoulos, R.K. Edwards, and P.G. Wahlbeck, J. Phys. Chem., 69, 2510-2515 (1965). 71Lan: N.A. Landin, L.A. Izhvanov, A.S. Chernikov, and V.P. Kalinin, Russ. J. Inorg. Chem., 16, 274-276 (1971). 71Spe: F.H. Spedding and B.J. Beaudry, J. Less-Common Met., 25, 61-73 (1971). 72Bea: A.G. Beattie, J. Appl Phys., 43, 3219-3221 (1972). 72Fed: V.N. Fedeyev, Izv. Akad. Nauk SSSR, 5, 210-214 (1972) in Russian; TR: Russ. Metall., 5, 148-151 (1972). 75Bea: B.J. Beaudry and F.H. Spedding, Metall. Trans. B, 6, 419-427 (1975). 79And: D.L. Anderson, R.G. Barnes, S.O. Nelson, and D.R. Torgeson, Phys. Lett., A, 74, 427-431 (1979). 80And: D.L. Anderson, R.G. Barnes, D.T. Peterson, and D.R. Torgeson, Phys. Rev. B, 21, 2625-2626 (1980). 80Beg: G.M. Begun, J.F. Lan, and J.T. Bell, J. Chem. Phys., 72, 2959-2966 ( 1980). 80Kha: D. Khatamian, W.A. Kamitakahara, R.G. Barnes, and D.T. Peterson, Phys. Rev. B, 21, 2622-2624 (1980). 81Kha: D. Khatamian, C. Stassis, and B.J. Beaudry, Phys. Rev. B, 23, 624-627 ( 1981). 82Bon: J.E. Bonnet, C. Juckum, and A. Lucasson, J. Phys. F, 12, 699-711 (1982). 84Bon: J.E. Bonnet and R. Griessen, J. Less-Common Met., 103-133 (1984). 84Gol: J.A. Goldstone, J. Eckert, P.M. Richards, and E.L. Venturini, Solid State Commun., 49, 475-478 (1984). 86Bon: J.E. Bonnet, private communication (1986). Published in Bull. Alloy Phase Diagrams, 9(3), Jun 1988.Complete evaluation contains 5 figures, 5 tables, and 74 references. 1