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Title: High Temperature Corrosion of a Pt-30 wt.% Rh Alloy in a Phosphorizing Gas

Abstract

High temperature corrosion of a Pt-30 wt.% Rh alloy in a phosphorizing gas was isothermally investigated at 1285 K using a gas switching technique. Diffusion of P into the alloy created an outer layer of Pt-rich liquid and blocky (Pt, Rh) 2P precipitates along with an inner layer of fcc and (Pt, Rh) 2P plates in a cellular microstructure. Concentration profiles measured by SEM-WDS and EPMA across the layers at room temperature showed that there were three fcc phases: first was a 12 at.% Rh phase in the outer layer; second was a 37 at.% Rh phase in the cellular microstructure; and third was the initial 43 at.% Rh alloy. Also, the EPMA data registered approximately 0.1 at.% P in fcc of these layers. Based on the surrounding binary phase diagrams and the experimental data obtained in this study, a partial Pt-Rh-P phase diagram was constructed. A diffusion path for the corrosion microstructure was drawn on the partial phase diagram to help develop a step by step model for how the microstructure evolved. In conclusion, growth kinetics of the inner layer were used to calculate a P diffusivity of about 10 –12 m 2/s in the Pt-Rh alloy at 1285more » K, suggesting rapid diffusion by either an interstitial or interstitialcy mechanism.« less

Authors:
 [1];  [1];  [2];  [3]
  1. National Energy Technology Lab. (NETL), Albany, OR (United States); AECOM, Albany, OR (United States)
  2. National Energy Technology Lab. (NETL), Albany, OR (United States)
  3. The Ohio State Univ., Columbus, OH (United States)
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Albany, OR (United States)
Sponsoring Org.:
FE; USDOE
OSTI Identifier:
1509706
Grant/Contract Number:  
FE0004000; Inter-Agency Working Group for Air Force Research Laboratory
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Phase Equilibria and Diffusion
Additional Journal Information:
Journal Volume: 39; Journal Issue: 6; Journal ID: ISSN 1547-7037
Publisher:
ASM International
Country of Publication:
United States
Language:
English
Subject:
concentration profiles; diffusion; diffusion paths; electron probe microanalysis (EPMA); equilibrium diagram

Citation Formats

Nakano, Anna, Nakano, Jinichiro, Bennett, James P., and Morral, John E. High Temperature Corrosion of a Pt-30 wt.% Rh Alloy in a Phosphorizing Gas. United States: N. p., 2018. Web. doi:10.1007/s11669-018-0684-6.
Nakano, Anna, Nakano, Jinichiro, Bennett, James P., & Morral, John E. High Temperature Corrosion of a Pt-30 wt.% Rh Alloy in a Phosphorizing Gas. United States. doi:10.1007/s11669-018-0684-6.
Nakano, Anna, Nakano, Jinichiro, Bennett, James P., and Morral, John E. Mon . "High Temperature Corrosion of a Pt-30 wt.% Rh Alloy in a Phosphorizing Gas". United States. doi:10.1007/s11669-018-0684-6. https://www.osti.gov/servlets/purl/1509706.
@article{osti_1509706,
title = {High Temperature Corrosion of a Pt-30 wt.% Rh Alloy in a Phosphorizing Gas},
author = {Nakano, Anna and Nakano, Jinichiro and Bennett, James P. and Morral, John E.},
abstractNote = {High temperature corrosion of a Pt-30 wt.% Rh alloy in a phosphorizing gas was isothermally investigated at 1285 K using a gas switching technique. Diffusion of P into the alloy created an outer layer of Pt-rich liquid and blocky (Pt, Rh)2P precipitates along with an inner layer of fcc and (Pt, Rh)2P plates in a cellular microstructure. Concentration profiles measured by SEM-WDS and EPMA across the layers at room temperature showed that there were three fcc phases: first was a 12 at.% Rh phase in the outer layer; second was a 37 at.% Rh phase in the cellular microstructure; and third was the initial 43 at.% Rh alloy. Also, the EPMA data registered approximately 0.1 at.% P in fcc of these layers. Based on the surrounding binary phase diagrams and the experimental data obtained in this study, a partial Pt-Rh-P phase diagram was constructed. A diffusion path for the corrosion microstructure was drawn on the partial phase diagram to help develop a step by step model for how the microstructure evolved. In conclusion, growth kinetics of the inner layer were used to calculate a P diffusivity of about 10–12 m2/s in the Pt-Rh alloy at 1285 K, suggesting rapid diffusion by either an interstitial or interstitialcy mechanism.},
doi = {10.1007/s11669-018-0684-6},
journal = {Journal of Phase Equilibria and Diffusion},
number = 6,
volume = 39,
place = {United States},
year = {2018},
month = {10}
}

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