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Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation

The copper harmonic structure, which consists of a coarse-grained “core” surrounded by a three-dimensional continuously connected fine-grained “shell,” exhibits both high ductility and high strength. In the present study, dislocation interactions at the shell–core boundary in the copper harmonic str...

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Autores principales: Paul, Viola, Wakeda, Masato, Ameyama, Kei, Ota-Kawabata, Mie, Ohmura, Takahito
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8510059/
https://www.ncbi.nlm.nih.gov/pubmed/34640060
http://dx.doi.org/10.3390/ma14195663
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author Paul, Viola
Wakeda, Masato
Ameyama, Kei
Ota-Kawabata, Mie
Ohmura, Takahito
author_facet Paul, Viola
Wakeda, Masato
Ameyama, Kei
Ota-Kawabata, Mie
Ohmura, Takahito
author_sort Paul, Viola
collection PubMed
description The copper harmonic structure, which consists of a coarse-grained “core” surrounded by a three-dimensional continuously connected fine-grained “shell,” exhibits both high ductility and high strength. In the present study, dislocation interactions at the shell–core boundary in the copper harmonic structure were directly measured using nanoindentation and microstructural observations via kernel average misorientation (KAM) to further understand the reason for its excellent mechanical properties. KAM analysis showed that the dislocation density in the vicinity of the shell–core boundary within the core region gradually increases with increasing plastic strain. The variation in the nanohardness exactly corresponds to the KAM, indicating that the higher strength is primarily caused by the higher dislocation density. The critical load for nanoindentation-induced plasticity initiation was lower at the shell–core boundary than at the core–core boundary, indicating a higher potency of dislocation emission at the shell–core boundary. Because dislocation–dislocation interactions are one of the major causes of the increase in the flow stress leading to higher strain hardening rates during deformation, the excellent balance between strength and ductility is attributed to the higher potency of dislocation emission at the shell–core boundary.
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spelling pubmed-85100592021-10-13 Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation Paul, Viola Wakeda, Masato Ameyama, Kei Ota-Kawabata, Mie Ohmura, Takahito Materials (Basel) Communication The copper harmonic structure, which consists of a coarse-grained “core” surrounded by a three-dimensional continuously connected fine-grained “shell,” exhibits both high ductility and high strength. In the present study, dislocation interactions at the shell–core boundary in the copper harmonic structure were directly measured using nanoindentation and microstructural observations via kernel average misorientation (KAM) to further understand the reason for its excellent mechanical properties. KAM analysis showed that the dislocation density in the vicinity of the shell–core boundary within the core region gradually increases with increasing plastic strain. The variation in the nanohardness exactly corresponds to the KAM, indicating that the higher strength is primarily caused by the higher dislocation density. The critical load for nanoindentation-induced plasticity initiation was lower at the shell–core boundary than at the core–core boundary, indicating a higher potency of dislocation emission at the shell–core boundary. Because dislocation–dislocation interactions are one of the major causes of the increase in the flow stress leading to higher strain hardening rates during deformation, the excellent balance between strength and ductility is attributed to the higher potency of dislocation emission at the shell–core boundary. MDPI 2021-09-29 /pmc/articles/PMC8510059/ /pubmed/34640060 http://dx.doi.org/10.3390/ma14195663 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Communication
Paul, Viola
Wakeda, Masato
Ameyama, Kei
Ota-Kawabata, Mie
Ohmura, Takahito
Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title_full Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title_fullStr Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title_full_unstemmed Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title_short Local Deformation Behavior of the Copper Harmonic Structure near Grain Boundaries Investigated through Nanoindentation
title_sort local deformation behavior of the copper harmonic structure near grain boundaries investigated through nanoindentation
topic Communication
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8510059/
https://www.ncbi.nlm.nih.gov/pubmed/34640060
http://dx.doi.org/10.3390/ma14195663
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