Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 34: Topical Session Bulk Nanostrucured Materials VII - Mechanical Properties II
MM 34.4: Vortrag
Mittwoch, 28. März 2012, 12:30–12:45, H 0107
Pressure dependence of plasticity in nanocrystalline Pd90Au10 — •Christian Braun, Manuel Grewer, and Rainer Birringer — Universität des Saarlandes, FR 7.2 Experimentalphysik, Campus D2.2, 66123 Saarbrücken
The recently introduced miniaturisation of the shear-compression-specimen [1] allows the mechanical testing of small samples such as inert gas condensed nanocrystalline materials via dominant shear-deformation. By means of a variation of the shear-angle, it is possible to vary the shear-compression-ratio and the hydrostatic pressure P in the deformation zone. The analysis of the pressure dependence of plastic flow relies on two prominent parameter, the pressure activation volume Δ vP and the Mohr-Coulomb coefficient µ. For nc Pd90Au10-samples with an average grain diameter of about 10 nm, we determined Δ vP to 1-2 b3, where Δ vP is given as Δ vP = ∂σ/∂ PΔ vσ and Δ vσ is the shear activation volume obtained from stress-strain-curves taken at different strain rates [2]. Applying the Mohr-Coulomb yield criterion, we deduced a friction coefficient µ in the order of 0.1-0.2 which is comparable to values obtained for a variety of bulk-metallic-glasses [3]. Analogies between the deformation behaviour of bulk-metallic-glasses and nanocrystalline materials in the limit of small grain sizes will be discussed.
[1] M. Ames, J. Markmann, R. Birringer, Mater. Sci. Eng. A 528, 526 (2010), [2] A.S. Argon, Strengthening Mechanisms in Crystal Plasticity, OUP (2007), [3] Z.F. Zhang, J. Eckert, L. Schultz, Acta Mater. 51, 1167(2003)