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Title: Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels

Abstract

Doping with interstitials influences the grain boundary (GB) composition of metallic alloys, enabling changes in elemental GB enrichment, grain size, and mechanical properties or even promoting nanoparticle formation. Yet, little efforts on these doping effects have been made in oxide dispersion-strengthened (ODS) steels. In this paper, by combining advanced microscopy techniques, we studied the impact of interstitial concentration and extrusion temperature on the GB structure-dependent solute segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic Fe–14Cr (wt%) ODS steels fabricated by ball milling. We found that doping with high carbon and oxygen contents causes the GB to be decorated with the interstitials and promotes nanoparticle formation along the GBs, thereby retarding capillary-driven grain coarsening. This effect performs twofold, through grain size refinement and particle hardening. For samples with low interstitial contents, altering the extrusion temperature does not significantly change the material's mechanical properties and microstructure or the nonstoichiometric chemistry of nanoparticles, which are highly stable at high temperatures. Finally and further, for all the samples, Y–Al oxides in the initial precipitation stages rapidly become coarsened at high temperatures, as Al weakens the thermal stability of nanoparticles, thereby transforming them to core-shell structures with Y-Al-rich cores and Ti-O-rich shells in the latermore » precipitation stages.« less

Authors:
 [1];  [2]; ORCiD logo [3];  [4]
  1. Pohang Univ. of Science and Technology (POSTECH) (Korea, Republic of). National Inst. for Nanomaterials Technology
  2. Univ. of Oxford (United Kingdom). Dept. of Materials
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  4. Hanbat National Univ., Daejeon (Korea, Republic of). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pohang Univ. of Science and Technology (POSTECH) (Korea, Republic of); Hanbat National Univ., Daejeon (Korea, Republic of)
Sponsoring Org.:
USDOE; National Research Foundation of Korea (NRF); Ministry of Science and ICT (MSIT) (Korea, Republic of); Civil-Military Technology Cooperation Program (Korea, Republic of)
OSTI Identifier:
1463984
Grant/Contract Number:  
[AC05-00OR22725; 2018R1A2B6004490; 2018R1C1B6008585; 17-CM-MA-06]
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
[ Journal Volume: 153]; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ODS ferritic steel; grain-boundary segregation; nanoparticles; atom probe tomography

Citation Formats

Seol, Jae Bok, Haley, Daniel, Hoelzer, David T., and Kim, Jeoung Han. Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels. United States: N. p., 2018. Web. doi:10.1016/j.actamat.2018.04.046.
Seol, Jae Bok, Haley, Daniel, Hoelzer, David T., & Kim, Jeoung Han. Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels. United States. doi:10.1016/j.actamat.2018.04.046.
Seol, Jae Bok, Haley, Daniel, Hoelzer, David T., and Kim, Jeoung Han. Sat . "Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels". United States. doi:10.1016/j.actamat.2018.04.046. https://www.osti.gov/servlets/purl/1463984.
@article{osti_1463984,
title = {Influences of interstitial and extrusion temperature on grain boundary segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic steels},
author = {Seol, Jae Bok and Haley, Daniel and Hoelzer, David T. and Kim, Jeoung Han},
abstractNote = {Doping with interstitials influences the grain boundary (GB) composition of metallic alloys, enabling changes in elemental GB enrichment, grain size, and mechanical properties or even promoting nanoparticle formation. Yet, little efforts on these doping effects have been made in oxide dispersion-strengthened (ODS) steels. In this paper, by combining advanced microscopy techniques, we studied the impact of interstitial concentration and extrusion temperature on the GB structure-dependent solute segregation, Y-Ti-O nanofeatures, and mechanical properties of ferritic Fe–14Cr (wt%) ODS steels fabricated by ball milling. We found that doping with high carbon and oxygen contents causes the GB to be decorated with the interstitials and promotes nanoparticle formation along the GBs, thereby retarding capillary-driven grain coarsening. This effect performs twofold, through grain size refinement and particle hardening. For samples with low interstitial contents, altering the extrusion temperature does not significantly change the material's mechanical properties and microstructure or the nonstoichiometric chemistry of nanoparticles, which are highly stable at high temperatures. Finally and further, for all the samples, Y–Al oxides in the initial precipitation stages rapidly become coarsened at high temperatures, as Al weakens the thermal stability of nanoparticles, thereby transforming them to core-shell structures with Y-Al-rich cores and Ti-O-rich shells in the later precipitation stages.},
doi = {10.1016/j.actamat.2018.04.046},
journal = {Acta Materialia},
number = ,
volume = [153],
place = {United States},
year = {2018},
month = {4}
}

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