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Microstructural dependence of the fracture toughness of metallic thin films: A bulge test and atomistic simulation study on single-crystalline and polycrystalline silver films

Preiß, Eva I.; Lyu, Hao; Liebig, Jan P.; Richter, Gunther; Gannott, Florentina; Gruber, Patric A. 1; Göken, Mathias; Bitzek, Erik; Merle, Benoit
1 Karlsruher Institut für Technologie (KIT)


The microstructure contribution to the very low fracture toughness of freestanding metallic thin films was investigated by bulge fracture tests on 200-nm-thick {100} single-crystalline and polycrystalline silver films. The single-crystalline films exhibited a significantly lower fracture toughness value (KIC= 0.88 MPa m1/2) than their polycrystalline counterparts (KIC= 1.45 MPa m1/2), which was rationalized by the observation of an unusual crack initiation behavior—characterized by twinning in front of the notch tip—during in situ testing in the atomic force microscope. Twinning was also observed as a dominant deformation mechanism in atomistic simulations. This twinning tendency is explained by comparing the resolved shear stresses acting on the leading partial dislocation and the full dislocation, which allows to develop a size- and orientation-dependent twinning criterion. The fracture toughness of polycrystalline samples was found to be higher because of the energy dissipation associated with full dislocation plasticity and because of crack meandering along grain boundaries.

Verlagsausgabe §
DOI: 10.5445/IR/1000105838
Veröffentlicht am 17.02.2020
DOI: 10.1557/jmr.2019.262
Zitationen: 7
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Werkstoff- und Biomechanik (IAM-WBM)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 10.2019
Sprache Englisch
Identifikator ISSN: 0884-2914, 2044-5326
KITopen-ID: 1000105838
Erschienen in Journal of materials research
Verlag Cambridge University Press (CUP)
Band 34
Heft 20
Seiten 3483–3494
Vorab online veröffentlicht am 18.09.2019
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