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In Situ TEM Observation of Cooperative Grain Rotations and the Bauschinger Effect in Nanocrystalline Palladium

Kashiwar, Ankush 1; Hahn, Horst 1; Kübel, Christian ORCID iD icon 1,2
1 Institut für Nanotechnologie (INT), Karlsruher Institut für Technologie (KIT)
2 Karlsruhe Nano Micro Facility (KNMF), Karlsruher Institut für Technologie (KIT)

Abstract:

We report on cooperative grain rotation accompanied by a strong Bauschinger effect in nanocrystalline (nc) palladium thin film. A thin film of nc Pd was subjected to cyclic loading–unloading using in situ TEM nanomechanics, and the evolving microstructural characteristics were investigated with ADF-STEM imaging and quantitative ACOM-STEM analysis. ADF-STEM imaging revealed a partially reversible rotation of nanosized grains with a strong out-of-plane component during cyclic loading–unloading experiments. Sets of neighboring grains were shown to rotate cooperatively, one after the other, with increasing/decreasing strain. ACOM-STEM in conjunction with these experiments provided information on the crystallographic orientation of the rotating grains at different strain levels. Local Nye tensor analysis showed significantly different geometrically necessary dislocation (GND) density evolution within grains in close proximity, confirming a locally heterogeneous deformation response. The GND density analysis revealed the formation of dislocation pile-ups at grain boundaries (GBs), indicating the generation of back stresses during unloading. ... mehr


Verlagsausgabe §
DOI: 10.5445/IR/1000134556
Veröffentlicht am 30.06.2021
Originalveröffentlichung
DOI: 10.3390/nano11020432
Scopus
Zitationen: 1
Web of Science
Zitationen: 1
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Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 2079-4991
KITopen-ID: 1000134556
HGF-Programm 43.35.01 (POF IV, LK 01) Platform for Correlative, In Situ & Operando Charakterizat.
Weitere HGF-Programme 43.31.01 (POF IV, LK 01) Multifunctionality Molecular Design & Material Architecture
Erschienen in Nanomaterials
Verlag MDPI
Band 11
Heft 2
Seiten 432
Vorab online veröffentlicht am 09.02.2021
Schlagwörter nanocrystalline metals; nanomechanical behavior; plasticity; thin films; Bauschinger effect; deformation mechanisms; grain rotation; in situ transmission electron microscopy (TEM); automated crystal orientation mapping in STEM (ACOM-STEM)
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