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Thermodynamic modeling of the platinum yttrium system

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Thermodynamic modeling of the platinum yttrium system

  1. 1. Thermodynamic Modeling of the Platinum-Yttrium system Madeline Boyer Undergrad presentation Summer 2011 1
  2. 2. Outline• Brief introduction of summer goals• Summary of Pt-Y system – Literature review – Discussion of experimental data • Calculations of enthalpy values• Thermodynamic Data and ThermoCalc – Learning process – Setting up ThermoCalc, challenges• Modeling Results• Future goals 2
  3. 3. My history with 304 PhasesDiffusion couples (Mg-Al) with Lauren Skrabski Central South University Resulted in a paper with Laura Jean Lucca 3
  4. 4. Madeline’s Timeline 2011 June July August Literature [1] Milestone 1: Completing review the Literature reviewThermo calc [2]:Moving from Mg-Ni system to Pt-Ymodeling of Learning ThermoCalc Pt-Y Modeling of Pt-Y [3] Finish Pt-Y diagram system 1st Batch [6]: 1000hrs [7]:2000hrs 2nd BatchLauren‘s Steel [8]:begin [11]:1000hrs [12]:2000hrs [9]:100 hrs [10]:200hrs 4
  5. 5. Motivation for this work• Usefulness for others in the lab • Possible work with first-principles in the future• Contributing to the ONR project • Pt-Y system has not been modeled• Learning project • Stepping stone for undergraduate thesis • Polymer modeleing in ThermoCalc as senior project 5
  6. 6. Literature Review • Drawn based on Er-Pt systemPalenzona, Bull. Alloy Phase Diag., 1990 6
  7. 7. Literature Review Discussion• Previous work: – Holcombe (1976): melting point of the eutectic – Moffatt (1971): Pt-Er system – Vorona (1983): confirmed the existence of 10 compounds at 600 °C – Mediema (1975): calculated 3 different enthalpy of formation values at .25 composition Y in Pt, .5 and .75 – Hellwig (1978): Experimental Gibbs energy for two compounds 7
  8. 8. Limited experimental enthalpy of formation values found in the literature Compounds Composition Mediema DfH Hellwig DfH (kJ-mol-atom) (kJ-mol-atom) Pt5Y 0.167 -64.33 Pt3Y 0.25 -87.864 -96.71 Pt2Y 0.333 Pt4Y3 0.429 PtY 0.5 -121.34 Pt4Y5 0.556 Pt3Y5 0.625 PtY2 0.667 Pt3Y7 0.7 PtY3 0.75 -66.94L.Hellwig, Kernforschungszentrum Karlsruhe,.1978A.R Miedema, Journal of Less Common Metals,.1976 8
  9. 9. Used experimental values to create aconvex hull as starting point for modeling 9
  10. 10. ThermoCalc: Macros, Pops, and Parrots• Friendly Thermodynamics with Alyson• Macro files and Pop files• Optimizing and Modeling – Brief summary of Models used 10
  11. 11. Entropy Calculations for the 8 other compounds• ∆G = ∆H - ∆S*T• ∆G = A + B*T• Hellwig(1978) – ∆fGPt5Y = -385.97 + 5.4e10-3*T kJ/mol – ∆fGPt3Y = -386.83 + 19.6e10-3*T kJ/mol• As a starting point, calculate A/B ratio for all compounds based on known experimental data L.Hellwig, Kernforschungszentrum Karlsruhe,.1978 11
  12. 12. As part of the learning process forThermoCalc, learn to plot with no parameters Liquid bcc fcc hcp 12
  13. 13. Creating a setup.tcm and defining the compounds• Macro file set up: Declaring all compounds• Example:PT5Y2 SUBLATTICES, SITES 5: 1 CONSTITUENTS: PT : Y G(PT5Y,PT:Y;0) - 5 H298(FCC_A1,PT;0) – H298(HCP_A3,Y;0) = + 5*GHSERPT + GHSERYY + V1 + V2*T 13
  14. 14. Liquid Parameters L(LIQUID,PT,Y;0) = +V41+V42*T L(LIQUID,PT,Y;1) = +V43+V44*T L(LIQUID,PT,Y;2) = +V45+V46*TG A B Alyson Lieser, “Friendly Thermodynamics” (2011) 14
  15. 15. ThermoCalc Setup: Pop file ACM 1 ACM 2APR1 APR2 APR3 APR4 APR5 AEP2 APR6 APR7AEPT APR8 AEYY 15
  16. 16. First step of modeling with twocompounds from experimental data Liquid bcc Pt5Y Pt3Y fcc hcp 16
  17. 17. Current modeling of the Pt-Y system Liquid PtY Pt5Y Pt3Y bcc fcc hcp 17
  18. 18. Future Goals• Scaling entropy values down to get correct temperatures for invariant reactions – Focus on eutectic reactions• New challenges – Possible modeling of another system in the fall – Working towards possible modeling with polymers. 18
  19. 19. AcknowledgementsI would like to thank so very much: Chelsey Zacherl and Alyson LieserAnd also Brian VanLeeuwan, Bi Cheng Zhou, Arkapol Saengdeejing, and Dr. Liu 19
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  21. 21. Calculated Enthalpy valuesCompound Composition (percent Y) Estimated DH (kj-mol) Pt5Y 0.167 -64.33 Pt3Y 0.25 -96.71 Pt2Y 0.333 -106.5 Pt4Y3 0.429 -115.5 PtY 0.5 -121.34 Pt4Y5 0.556 -111.5 Pt3Y5 0.625 -97 PtY2 0.667 -86.5 Pt3Y7 0.7 -78.5 PtY3 0.75 -66.94 Red number: Experimental 21
  22. 22. Entropy Values Composition CalculatedCompounds (Percent Y) Estimated Enthalpy entropy value Pt5Y 0.167 -64.33 0.0009 A/B = ratio Pt3Y 0.25 -96.71 0.0049 Pt2Y 0.333 -106.5 0.002335 Pt4Y3 0.429 -115.5 0.002532 PtY 0.5 -121.34 0.00266 Pt4Y5 0.556 -111.5 0.002445 Pt3Y5 0.625 -97 0.002127 PtY2 0.667 -86.5 0.001897 Pt3Y7 0.7 -78.5 0.001721 PtY3 0.75 -66.94 0.001468 22
  23. 23. Current model parameters 23
  24. 24. 24

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