Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 65: Topical session: X-ray and neutron scattering in materials science VI - Which orientations can we expect for elongated particles in self-confined systems?
MM 65.1: Topical Talk
Freitag, 4. April 2014, 11:45–12:15, BAR 205
Which orientations can we expect for elongated particles in self-confined systems? — •Ulla Vainio1, Thea Schnoor2, Jürgen Markmann1,2, Ke Wang2, Karl Schulte2, Jörg Weissmüller1,2, Erica Lilleodden1, Andreas Schreyer1, and Martin Müller1 — 1Helmholtz-Zentrum Geesthacht — 2Technische Universität Hamburg-Harburg
Many new novel composite materials aim at orienting particles within a matrix in a preferred direction. It is commonly known that orientations of crystals in metals have a strong impact on the mechanical properties of the metals, and we expect the same for nanocomposite materials in which the orientation of particles is to a large extent limited by self-confinement. An example of a self-confined system is a carbon nanotube forest with its long cylindrical nanotubes growing away from a substrate and creating a seemingly homogeneous array of nanotubes with vertical alignment. Here we show that this vertical alignment cannot be described accurately by any of the commonly used distribution functions such as Gaussian or Lorentzian. Instead, the orientation distribution was measured using small-angle X-ray scattering (SAXS) and was fitted best by the generalized normal distribution, which is an extension to the Gaussian and allows one more degree of freedom. In another example we use small-angle neutron scattering (SANS) to study the orientation of ligaments in a nanoporous gold composite. In this case we observe the nanostructure after applying compressive deformation and can follow the changes in the orientation of the ligaments.