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Microstructure-dependent deformation behaviour of bcc-metals – indentation size effect and strain rate sensitivity

Maier, Verena ; Schunk, Christopher ; Göken, Mathias ; Durst, Karsten (2015)
Microstructure-dependent deformation behaviour of bcc-metals – indentation size effect and strain rate sensitivity.
In: Philosophical Magazine, 95 (16-18)
doi: 10.1080/14786435.2014.982741
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

In this work, the indentation size effect and the influence of the microstructure on the time-dependent deformation behaviour of body-centred cubic (bcc) metals are studied by performing nanoindentation strain rate jump tests at room temperature. During these experiments, the strain rate is abruptly changed, and from the resulting hardness difference the local strain rate sensitivity has been derived. Single-crystalline materials exhibit a strong indentation size effect; ultrafine-grained metals have nearly a depth-independent hardness. Tungsten as a bcc metal shows the opposite behaviour as generally found for face-centered cubic metals. While for UFG-W only slightly enhanced strain rate sensitivity was observed, SX-W exhibits a pronounced influence of the strain rate on the resulting hardness at room temperature. This is due to the effects of the high lattice friction of bcc metals at low temperatures, where the thermally activated motion of screw dislocations is the dominating deformation mechanisms, which causes the enhanced strain rate sensitivity. For the SX-materials, it was found that the degree of the indentation size effect directly correlates with the homologous testing temperature and thus, the material specific parameter of the critical temperature T-c. However, for the resultant strain rate sensitivity no depth-dependent change was found.

Typ des Eintrags: Artikel
Erschienen: 2015
Autor(en): Maier, Verena ; Schunk, Christopher ; Göken, Mathias ; Durst, Karsten
Art des Eintrags: Bibliographie
Titel: Microstructure-dependent deformation behaviour of bcc-metals – indentation size effect and strain rate sensitivity
Sprache: Englisch
Publikationsjahr: 23 Juni 2015
Verlag: TAYLOR & FRANCIS LTD, England
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Philosophical Magazine
Jahrgang/Volume einer Zeitschrift: 95
(Heft-)Nummer: 16-18
DOI: 10.1080/14786435.2014.982741
Kurzbeschreibung (Abstract):

In this work, the indentation size effect and the influence of the microstructure on the time-dependent deformation behaviour of body-centred cubic (bcc) metals are studied by performing nanoindentation strain rate jump tests at room temperature. During these experiments, the strain rate is abruptly changed, and from the resulting hardness difference the local strain rate sensitivity has been derived. Single-crystalline materials exhibit a strong indentation size effect; ultrafine-grained metals have nearly a depth-independent hardness. Tungsten as a bcc metal shows the opposite behaviour as generally found for face-centered cubic metals. While for UFG-W only slightly enhanced strain rate sensitivity was observed, SX-W exhibits a pronounced influence of the strain rate on the resulting hardness at room temperature. This is due to the effects of the high lattice friction of bcc metals at low temperatures, where the thermally activated motion of screw dislocations is the dominating deformation mechanisms, which causes the enhanced strain rate sensitivity. For the SX-materials, it was found that the degree of the indentation size effect directly correlates with the homologous testing temperature and thus, the material specific parameter of the critical temperature T-c. However, for the resultant strain rate sensitivity no depth-dependent change was found.

Freie Schlagworte: nanoindentation, bcc metals, deformation behaviour, strain rate sensitivity, indentation size effect
Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Physikalische Metallkunde
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft
11 Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum: 08 Mär 2016 09:53
Letzte Änderung: 08 Mär 2016 09:53
PPN:
Sponsoren: Financial support was provided by the German Research Council (DFG), which, within the framework of its 'Excellence Initiative' supports the Cluster of Excellence "Engineering of Advanced Materials" at the University of Erlangen-Nurnberg., Financial support was provided at the Montanuniversitat Leoben by the Zukunftsfond Steiermark within the project 6019 "Nanofatigue".
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