Para-equilibrium Phase Diagrams, μH − XM, for Pd Alloy-H Systems

  • Ted B. FlanaganEmail author
  • W. A. Oates


There are many papers concerning H in Pd alloys but their corresponding para-equilibrium phase diagrams have not been given. Para-equilibrium is the most common condition under which data are obtained for Pd alloy-H systems and refers to the condition where the mobile interstitial species (H) reaches equlibrium within an immobile metal alloy framework. Based on these para-equilibrium phase diagrams, an explanation will be offered for the experimental observation that the terminal hydrogen solubilities are always greater in fcc, substitutional Pd alloys than in Pd itself where this term refers to the limiting solubility of H in the dilute phase before the hydride phase forms.


Pd alloys hydrogen para-equilibrium 



  1. 1.
    Y. Sakamoto, F. Chen, M. Ura, and T. Flanagan, Thermodynamic Properties for Solution of Hydrogen in Palladium-Based Binary Alloys. Ber. Bunsenges. Phys. Chem., 1995, 99, p 807CrossRefGoogle Scholar
  2. 2.
    A. Hultgren, Isothermal Transformation of Austenite, Trans. ASM, 1947, 39, p 915Google Scholar
  3. 3.
    M. Hillert, and J. Agren, On the Definitions of Paraequilibrium and Orthoequilibrium, Scr. Mater., 2004, 50, p 697CrossRefGoogle Scholar
  4. 4.
    T. Flanagan, W. Oates, and S. Kishimoto, Solvus Thermodynamics of Metal-Hydrogen Interstitial Solutions, Acta Met., 1983, 31, p 199CrossRefGoogle Scholar
  5. 5.
    W. Oates, and T. Flanagan, The Terminal Solubility of Hydrogen in Niobium-Tantalum Alloys, Acta Met., 1985, 33, p 693CrossRefGoogle Scholar
  6. 6.
    S. Lim, T. Flanagan, and W. Oates, On the Terminal Solubility of Hydrogen in NbV alloys, Acta Met., 1988, 36, p 2047CrossRefGoogle Scholar
  7. 7.
    Y. Sakamoto, K. Yuwasa, and K. Hirayama, X-Ray Investigation of the Absorption of Hydrogen by Several Palladium and Nickel Solid Solution Alloys, J. Less-Common Met., 1982, 88, p 115CrossRefGoogle Scholar
  8. 8.
    A. Irodova, V. Glazkov, V. Somenkov, V. Antonov, and E. Ponyatovsky, Hydrogen Caused Ordering in PdAg Alloy, Z. Phys, 1989 163, p 53-57CrossRefGoogle Scholar
  9. 9.
    M.L.H. Wise, J.P.G. Farr, and I.R. Harris, X-Ray Studies of the \(\alpha /\beta\) Miscibility Gaps of Some Palladium Solid Solution-Hydrogen Systems, J. Less-Common Met., 1975, 41, p 115-127CrossRefGoogle Scholar
  10. 10.
    Y. Sakamoto, K. Baba, and T. Flanagan, The Effect of Alloying of Palladium on the Hydrogen-Palladium Miscibility Gap, Z. Phys, 1988, 158, p 223CrossRefGoogle Scholar
  11. 11.
    J. Kirkwood, and I. Oppenheim, Chemical Thermodynamics, McGraw-Hill, New York, 1961Google Scholar
  12. 12.
    W. Oates, and T. Flanagan, The Solubility of Hydrogen in Transition Metals and Their Alloys, Prog. Solid State Chem., 1981, 13, p 193CrossRefGoogle Scholar
  13. 13.
    W. Oates, and T. Flanagan, Thermodynamic Properties of Regular Interstitial Solutions, J. Mat. Sci., 1981, 16, p 3235ADSCrossRefGoogle Scholar
  14. 14.
    T. Flanagan, D. Wang, and S. Luo, Thermodynamics of H in Disordered Pd-Ag Alloys from Calorimetric and Equilibrium Pressure–Composition–Temperature Measurements. J. Phys. Chem. C, 2007, 111, p 10723-10735CrossRefGoogle Scholar
  15. 15.
    E. Raub, H. Beeskow, and D. Menzel, Palladium Rhodium Alloys and Allotropy of Rhodium, Z. Metallkde, 1959, 50, p 426Google Scholar
  16. 16.
    T. Tkacz, High Pressure Studies of the Rhodium-Hydrogen System in Diamond Anvil Cell, J. Chem. Phys., 1998, 108, p 2084ADSCrossRefGoogle Scholar
  17. 17.
    B. Baranowski, and K. Bochenska, The free energy and entropy of formation of nickel hydride, Zeit. Phys. Chem. N.F., 1965, 45, p 140CrossRefGoogle Scholar
  18. 18.
    B. Baranowski, S. Majchrzak, and T. Flanagan, High-Pressure Investigation of the Rhodium/Palladium/Hydrogen System, J. Phys. Chem., 1973, 77, p 35CrossRefGoogle Scholar
  19. 19.
    T. Flanagan, and J. Lynch, Thermodynamics of a Gas in Equilibrium with Two Nonstoichiometric Condensed Phases—Application to Metal/Hydrogen Systems, J. Phys. Chem., 1975, 79, p 463-814Google Scholar
  20. 20.
    E. Wicke, and H. Brodowsky, in Hydrogen in Metals II, vol. 73, G. Alefeld, and J. Völkl, Ed., Springer, Berlin, 1978Google Scholar
  21. 21.
    W. Luo, and T. Flanagan, Correlations between Phase Diagrams and Thermodynamic Data for Metal Hydride Systems, J. Phase Equilib, 1994, 15, p 20CrossRefGoogle Scholar

Copyright information

© ASM International 2019

Authors and Affiliations

  1. 1.Chemistry DepartmentUniversity of VermontBurlingtonUSA
  2. 2.University of SalfordSalfordUK

Personalised recommendations