Post on 18-Dec-2014
description
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Thermodynamic Modeling of the Platinum-Yttrium system
Madeline BoyerUndergrad presentation
Summer 2011
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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
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My history with 304 Phases
Diffusion couples (Mg-Al) with Lauren Skrabski
Central South University
Resulted in a paper with Laura Jean Lucca
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Thermo calc modeling of
Pt-Y
[2]:Moving from Mg-Ni system to Pt-Y
[1] Milestone 1: Completing the Literature review
[3] Finish Pt-Y diagram
AugustJulyJuneLiterature review
Modeling of Pt-Y system
Lauren‘s Steel
[6]: 1000hrs
[9]:100 hrs
1st Batch
Learning ThermoCalc
2nd Batch
Madeline’s Timeline 2011
[7]:2000hrs
[10]:200hrs
[12]:2000hrs[8]:begin [11]:1000hrs
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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
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Literature Review
Palenzona, Bull. Alloy Phase Diag., 1990
• Drawn based on Er-Pt system
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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
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Limited experimental enthalpy of formation values found in the literature
Compounds Composition
Mediema DfH (kJ-mol-atom)
Hellwig DfH (kJ-mol-atom)
Pt5Y 0.167 -64.33Pt3Y 0.25 -87.864 -96.71Pt2Y 0.333Pt4Y3 0.429PtY 0.5 -121.34
Pt4Y5 0.556Pt3Y5 0.625PtY2 0.667Pt3Y7 0.7PtY3 0.75 -66.94
L.Hellwig, Kernforschungszentrum Karlsruhe,.1978
A.R Miedema, Journal of Less Common Metals,.1976
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Used experimental values to create a convex hull as starting point for modeling
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ThermoCalc: Macros, Pops, and Parrots
• Friendly Thermodynamics with Alyson• Macro files and Pop files• Optimizing and Modeling
– Brief summary of Models used
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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
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As part of the learning process for ThermoCalc, learn to plot with no parameters
Liquid
fcchcp
bcc
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Creating a setup.tcm and defining the compounds
• Macro file set up: Declaring all compounds• Example:
PT5Y 2 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
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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*T
A
G
BAlyson Lieser, “Friendly Thermodynamics” (2011)
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ThermoCalc Setup: Pop file
AEP2
AEPT
AEYY
APR1 APR3
APR6
APR4APR5
APR7
APR8
APR2
ACM1 ACM
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First step of modeling with two compounds from experimental data
Liquid
fcchcp
bcc
Pt5Y
Pt3Y
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Current modeling of the Pt-Y system
Liquid
fcchcp
bccPt5Y
Pt3Y Pt
Y
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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.
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Acknowledgements
I would like to thank so very much:Chelsey Zacherl and Alyson Lieser
And alsoBrian VanLeeuwan, Bi Cheng Zhou, Arkapol
Saengdeejing, and Dr. Liu
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Calculated Enthalpy values
Compound Composition (percent Y) Estimated DH (kj-mol)Pt5Y 0.167 -64.33Pt3Y 0.25 -96.71Pt2Y 0.333 -106.5Pt4Y3 0.429 -115.5PtY 0.5 -121.34
Pt4Y5 0.556 -111.5Pt3Y5 0.625 -97PtY2 0.667 -86.5Pt3Y7 0.7 -78.5PtY3 0.75 -66.94
Red number: Experimental
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Entropy Values
CompoundsComposition (Percent Y) Estimated Enthalpy
Calculated entropy value
Pt5Y 0.167 -64.33 0.0009Pt3Y 0.25 -96.71 0.0049Pt2Y 0.333 -106.5 0.002335Pt4Y3 0.429 -115.5 0.002532PtY 0.5 -121.34 0.00266
Pt4Y5 0.556 -111.5 0.002445Pt3Y5 0.625 -97 0.002127PtY2 0.667 -86.5 0.001897Pt3Y7 0.7 -78.5 0.001721PtY3 0.75 -66.94 0.001468
A/B = ratio
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Current model parameters
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