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Title: Specimen- and grain-size dependence of compression deformation behavior in nanocrystalline copper
Authors: Okamoto, Norihiko L.  kyouindb  KAKEN_id
Kashioka, Daisuke
Hirato, Tetsuji  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0003-3030-1632 (unconfirmed)
Inui, Haruyuki  kyouindb  KAKEN_id
Author's alias: 岡本, 範彦
Keywords: Dislocations (A)
Crystal plasticity (B)
Polycrystalline material (B)
Mechanical testing (C)
Focused ion beam (FIB) method
Issue Date: May-2014
Publisher: Elsevier Ltd.
Journal title: International Journal of Plasticity
Volume: 56
Start page: 173
End page: 183
Abstract: The compression deformation behavior of electrodeposited nanocrystalline copper pillars with average grain sizes (d) of 360, 100, and 34 nm has been investigated as a function of specimen size (D). The yield stress for nanocrystalline pillars with d = 360 and 100 nm does not depend on specimen size, exhibiting essentially the bulk yield stress until the specimen size is reduced down to the critical values ((D/d)∗ = 35 and 85), below which the yield stress decreases with the decrease in specimen size. In contrast, the yield stress for nanocrystalline pillars with d = 34 nm does not depend much on specimen size, exhibiting the bulk yield stress value for all specimen sizes investigated. The dominant deformation mechanism changes from dislocation glide for pillars with d = 360 and 100 nm to grain boundary diffusional creep for pillars with d = 34 nm. Grain-size induced softening occurs for pillars with d = 34 nm being consistent with the occurrence of change in deformation mechanisms, whereas the bulk yield stress for pillars with d = 360 and 100 nm increases with the decrease in grain size according to the classical Hall–Petch relationship. The critical (D/d)∗ values determined for nanocrystalline Cu pillars with d = 360 and 100 nm increases with the decrease in grain size so as to conform to the same power law scaling obtained for coarse-grained Cu polycrystals. This is the first indication that the specimen size-induced softening extends from micrometer to nanometer scales as far as the dominant deformation mechanism is dislocation glide. The considerably large critical (D/d)∗ values determined for nanocrystalline Cu pillars with d = 360 and 100 nm are discussed in terms of strain continuity among neighboring grains and the generation of geometrically necessary dislocations to maintain strain continuity at the grain boundaries.
Rights: © 2013 Elsevier Ltd.
この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。This is not the published version. Please cite only the published version.
URI: http://hdl.handle.net/2433/187145
DOI(Published Version): 10.1016/j.ijplas.2013.12.003
Appears in Collections:Journal Articles

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