Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 34: Nanomaterials
MM 34.2: Talk
Wednesday, March 14, 2018, 12:00–12:15, H 0106
Evaluation of tension-compression asymmetry in nanocrystalline PdAu using a Drucker-Prager type constitutive model — •Andreas Leibner1, Michael Deckarm1, Hasan Raza Syed2, Benjamin Klusemann2, and Rainer Birringer1 — 1Experimentalphysik, Universität des Saarlandes — 2Institut für Produkt- und Prozessinnovation, Leuphana Universität Lüneburg
There is ample evidence that the deformation behavior in nanocrystalline materials differs significantly from their coarse grained counterpart [1]. NC PdAu alloys at the low end of the nanoscale (≈ 10nm), where plasticity is predominantly mediated by grain boundaries [2], exhibit a distinct tension*compression asymmetry, which is unusual for fcc metals.
We performed deformation experiments utilizing a specific geometry. Tuning this geometry allows one to tailor the state of stress, in terms of compression to shear ratio, in the gauge section of the specimen. In order to evaluate the general deformation behavior of NC PdAu we employed FEM simulations and used a customized Drucker-Prager type constitutive material model.
In particular, we studied four different specimen geometries and varied the strain rate over five orders of magnitude down to 10−5. As a result, we find an intriguing variation of deformation and failure behavior. Nevertheless, we tried to explore whether or not a single material law is capable of capturing the stress strain evolutions.
[1] E.N. Hahn and M.A. Meyers, Mat. Sci. Eng. A, 646 (2015) 101-134 [2] M. Grewer et al., Mechanics of Materials, 114 (2017) 254-267