Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 28: Nanostructured Materials I
MM 28.4: Vortrag
Mittwoch, 24. März 2010, 11:00–11:15, H16
Mechanical spectroscopy of nanoparticle-reinforced, electrodeposited ultrafine-grained nickel — •Hans-Rainer Sinning1, Gabriele Vidrich2, and Werner Riehemann2 — 1Institut für Werkstoffe, Technische Universität Braunschweig — 2Institut für Werkstoffkunde und Werkstofftechnik, Technische Universität Clausthal
The grain size of electrodeposited ultrafine-grained nickel can be reduced down to the nanocrystalline range by adding ceramic nanoparticles like Al2O3 or SiO2. Mechanical spectroscopy (vibrating-reed technique at 200–800 Hz) reveals several different elastic and anelastic phenomena, all sensitive to annealing, which can be used to characterise the microstructural state, defects, and thermal stability of these nanocomposites. Preliminary results are shown on recovery effects (structural relaxation: increase of Young’s modulus and decrease of elastic energy dissipation in wide ranges of temperature), low-temperature mechanical loss peaks, and on the gradual development of amplitude-dependent damping components and of the magnetoelastic "ΔE effect" during grain coarsening. Differences in the annealing characteristics between these quantities, as well as between Ni samples with and without Al2O3 or SiO2 nanoparticles, respectively, are discussed with respect to underlying relaxation mechanisms and related processes of recovery and grain growth. In particular, in case of Al2O3 nanoparticles, two separate anelastic relaxation peaks near 170 and 120 K indicate, respectively, both the incorporation of hydrogen and the thermal generation of dislocations at the Ni/Al2O3 interfaces.