Strain-induced phase transformation of a thin Co film on flexible substrates

Author(s)
V. M. Marx, C. Kirchlechner, B. Breitbach, M. J. Cordill, D. M. Toebbens, T. Waitz, G. Dehm
Abstract

The strain-induced FCC to HCP phase transformation of a two phase Co film on polyimide was investigated by performing a tensile test in an X-ray diffractometer. During straining of the 2 mu m thick film, the intensity of the (002)(Fcc) peak continuously decreases at engineering strains between 2 and 8% and remains constant at higher strains. Complementary in situ tensile tests under an optical light microscope showed crack formation at 6.7% and crack saturation at around 10% engineering strain. The strain induced phase transformation starts before the first cracks form leading to a maximum lattice strain of approximately 0.9% as initiation strain measured from the (10 (1) over bar1)(HCP) peak with the sin(2)psi method which converts to a film stress of approximately 1270 +/- 150 MPa. It could be revealed that a strain induced phase transformation can enhance the ductility and therefore delay the crack onset of a thin cobalt film. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Organisation(s)
Physics of Nanostructured Materials
External organisation(s)
Max-Planck-Institut für Eisenforschung, Max-Planck-Gesellschaft, Montanuniversität Leoben, Österreichische Akademie der Wissenschaften (ÖAW), Helmholtz-Zentrum Berlin für Materialien und Energie, Helmholtz-Zentrum Dresden-Rossendorf
Journal
Acta Materialia
Volume
121
Pages
227-233
No. of pages
7
ISSN
1359-6454
DOI
https://doi.org/10.1016/j.actamat.2016.09.015
Publication date
12-2016
Peer reviewed
Yes
Austrian Fields of Science 2012
103018 Materials physics
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/straininduced-phase-transformation-of-a-thin-co-film-on-flexible-substrates(cf0543a3-51b1-4baf-bb4d-406c6ea9992c).html