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Title: Ab Initio Modeling of Bulk and Intragranular Diffusion in Ni Alloys

Abstract

importance for understanding mechanisms of grain boundary (GB) oxidation causing environmental degradation and cracking of Ni-base structural alloys. In this study, first-principles calculations of vacancy-mediated diffusion are performed across a wide series of alloying elements commonly used in Ni-based superalloys, as well as interstitial diffusion of atomic oxygen and sulfur in the bulk, at the (111) surface, <110> symmetric tilt GBs of Ni corresponding to model low- (Σ=3/(111)) and high-energy (Σ=9/(221)) GBs. A substantial enhancement of diffusion is found for all species at the high-energy GB as compared to the bulk and the low-energy GB, with Cr, Mn and Ti exhibiting remarkably small activation barriers (<0.1 eV; ~10 times lower than in the bulk). Calculations also show that the bulk diffusion mechanism and kinetics differ for oxygen and sulfur, with oxygen having a faster mobility and preferentially diffusing through the tetrahedral interstitial sites in Ni matrix where it can be trapped in a local minimum.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1208705
Report Number(s):
PNNL-SA-110894
48274; KC0202040
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry Letters, 6(9):1618-1623
Additional Journal Information:
Journal Name: Journal of Physical Chemistry Letters, 6(9):1618-1623
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Alexandrov, Vitali Y., Sushko, Maria L., Schreiber, Daniel K., Bruemmer, Stephen M., and Rosso, Kevin M. Ab Initio Modeling of Bulk and Intragranular Diffusion in Ni Alloys. United States: N. p., 2015. Web. doi:10.1021/acs.jpclett.5b00177.
Alexandrov, Vitali Y., Sushko, Maria L., Schreiber, Daniel K., Bruemmer, Stephen M., & Rosso, Kevin M. Ab Initio Modeling of Bulk and Intragranular Diffusion in Ni Alloys. United States. doi:10.1021/acs.jpclett.5b00177.
Alexandrov, Vitali Y., Sushko, Maria L., Schreiber, Daniel K., Bruemmer, Stephen M., and Rosso, Kevin M. Thu . "Ab Initio Modeling of Bulk and Intragranular Diffusion in Ni Alloys". United States. doi:10.1021/acs.jpclett.5b00177.
@article{osti_1208705,
title = {Ab Initio Modeling of Bulk and Intragranular Diffusion in Ni Alloys},
author = {Alexandrov, Vitali Y. and Sushko, Maria L. and Schreiber, Daniel K. and Bruemmer, Stephen M. and Rosso, Kevin M.},
abstractNote = {importance for understanding mechanisms of grain boundary (GB) oxidation causing environmental degradation and cracking of Ni-base structural alloys. In this study, first-principles calculations of vacancy-mediated diffusion are performed across a wide series of alloying elements commonly used in Ni-based superalloys, as well as interstitial diffusion of atomic oxygen and sulfur in the bulk, at the (111) surface, <110> symmetric tilt GBs of Ni corresponding to model low- (Σ=3/(111)) and high-energy (Σ=9/(221)) GBs. A substantial enhancement of diffusion is found for all species at the high-energy GB as compared to the bulk and the low-energy GB, with Cr, Mn and Ti exhibiting remarkably small activation barriers (<0.1 eV; ~10 times lower than in the bulk). Calculations also show that the bulk diffusion mechanism and kinetics differ for oxygen and sulfur, with oxygen having a faster mobility and preferentially diffusing through the tetrahedral interstitial sites in Ni matrix where it can be trapped in a local minimum.},
doi = {10.1021/acs.jpclett.5b00177},
journal = {Journal of Physical Chemistry Letters, 6(9):1618-1623},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {5}
}