Thermodynamic properties and phase equilibria for Pt-Rh alloys

K. T. Jacob, Shashank Priya, Yoshio Waseda

Research output: Contribution to journalArticle

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Abstract

The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state cell Pt-Rh, Rh + Rh2O3/(Y2O3)ZrO2/Pt 1-xRhx + Rh2O3, Pt-Rh The activity of platinum and the free energy, enthalpy, and entropy of mixing are derived. Activities exhibit moderate negative deviation from Raoult's law. The mixing properties can be represented by a pseudosubregular solution model in which excess entropy has the same type of functional dependence on composition as the enthalpy of mixing, ΔH = XRh (1 - XRh)[-10,970 + 45XRh] J/mol ΔSE = XRh (1 - XRh)[-3.80 + 1.55 × 10-2 XRh] J/mol·K The negative enthalpy of mixing obtained in this study is in qualitative agreement with predictions of semiempirical models of Miedema and co-workers and Colinet et al. The results of this study do not support the solid-state miscibility gap suggested in the literature, but are consistent with liquidus data within experimental uncertainty limits.

Original languageEnglish (US)
Pages (from-to)1545-1550
Number of pages6
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume29
Issue number6
DOIs
StatePublished - Jan 1 1998

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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