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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

2

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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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