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Title: Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe

Abstract

Grain boundaries often develop faceted morphologies in systems for which the interfacial free energy depends on the boundary inclination. Although the mesoscale thermodynamic basis for such morphological evolution has been extensively studied, the influence of line defects, such as secondary grain boundary dislocations, on the facet configurations has not been thoroughly explored. In this paper, through a combination of atomistic simulations and electron microscopic observations, we examine in detail the structure of an asymmetric Σ = 5 [001] grain boundary in well-annealed, body-centered cubic (BCC) Fe. The observed boundary forms with a hill-and-valley morphology composed of nanoscale {310} and {210} facets. Our analysis clarifies the atomic structure of the {310}/{210} facet junctions and identifies the presence of an array of secondary grain boundary dislocations that are localized to these junctions. Analysis of the Burgers vectors of the grain boundary dislocations, which are of type (1/5)<310> and (1/5)<120>, shows that the defect density is consistent with that required to accommodate a small observed angular deviation from the exact Σ = 5 orientation relationship. As a result, these observations and analysis suggest a crucial role for secondary grain boundary dislocations in dictating the length-scale of grain boundary facets, a consideration which hasmore » not been included in prior analyses of facet evolution and equilibrium facet length.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1393693
Alternate Identifier(s):
OSTI ID: 1333718
Report Number(s):
SAND-2016-11870J
Journal ID: ISSN 1359-6454; S1359645416308758; PII: S1359645416308758
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article: Published Article
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Name: Acta Materialia Journal Volume: 124 Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; grain-boundaries; dislocations; faceting; electron microscopy; atomistic modeling

Citation Formats

Medlin, D. L., Hattar, K., Zimmerman, J. A., Abdeljawad, F., and Foiles, S. M. Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe. United States: N. p., 2017. Web. doi:10.1016/j.actamat.2016.11.017.
Medlin, D. L., Hattar, K., Zimmerman, J. A., Abdeljawad, F., & Foiles, S. M. Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe. United States. https://doi.org/10.1016/j.actamat.2016.11.017
Medlin, D. L., Hattar, K., Zimmerman, J. A., Abdeljawad, F., and Foiles, S. M. 2017. "Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe". United States. https://doi.org/10.1016/j.actamat.2016.11.017.
@article{osti_1393693,
title = {Defect character at grain boundary facet junctions: Analysis of an asymmetric Σ = 5 grain boundary in Fe},
author = {Medlin, D. L. and Hattar, K. and Zimmerman, J. A. and Abdeljawad, F. and Foiles, S. M.},
abstractNote = {Grain boundaries often develop faceted morphologies in systems for which the interfacial free energy depends on the boundary inclination. Although the mesoscale thermodynamic basis for such morphological evolution has been extensively studied, the influence of line defects, such as secondary grain boundary dislocations, on the facet configurations has not been thoroughly explored. In this paper, through a combination of atomistic simulations and electron microscopic observations, we examine in detail the structure of an asymmetric Σ = 5 [001] grain boundary in well-annealed, body-centered cubic (BCC) Fe. The observed boundary forms with a hill-and-valley morphology composed of nanoscale {310} and {210} facets. Our analysis clarifies the atomic structure of the {310}/{210} facet junctions and identifies the presence of an array of secondary grain boundary dislocations that are localized to these junctions. Analysis of the Burgers vectors of the grain boundary dislocations, which are of type (1/5)<310> and (1/5)<120>, shows that the defect density is consistent with that required to accommodate a small observed angular deviation from the exact Σ = 5 orientation relationship. As a result, these observations and analysis suggest a crucial role for secondary grain boundary dislocations in dictating the length-scale of grain boundary facets, a consideration which has not been included in prior analyses of facet evolution and equilibrium facet length.},
doi = {10.1016/j.actamat.2016.11.017},
url = {https://www.osti.gov/biblio/1393693}, journal = {Acta Materialia},
issn = {1359-6454},
number = C,
volume = 124,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1016/j.actamat.2016.11.017

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Cited by: 39 works
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Works referencing / citing this record:

Grain boundary phases in bcc metals
journal, January 2018


Strain-Induced Asymmetric Line Segregation at Faceted Si Grain Boundaries
journal, July 2018


Segregation-Induced Nanofaceting Transition at an Asymmetric Tilt Grain Boundary in Copper
journal, December 2018


Polarization-dependent electromagnetic responses of ultrathin and highly flexible asymmetric terahertz metasurfaces
journal, January 2017