Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 36: Topical Session Bulk Nanostrucured Materials VIII - Functional Properties I

MM 36.1: Topical Talk

Wednesday, March 28, 2012, 15:00–15:30, H 0106

Functional Nanomaterials by SPD: Hydrogen Storage, Shape Memory Effect, and Thermoelectricity — •Michael Zehetbauer¹, Maciej Krystian¹, Gerhard Krexner², Thomas Waitz¹, Gerda Rogl^{1, 3}, and Peter Rogl³ — ¹Physics of Nanostructured Materials, Vienna University, Austria — ²Physics of Functional Materials, Vienna University, Austria — ³Institute of Physical Chemistry, Vienna University, Austria

From recent efforts to functionalise bulk nanostructured materials, those of hydrogen storage, shape memory effect , and thermoelectricity revealed the strongest progress so far. For SPD processed ZK60 Mg alloy, the hydrogen adsorption/desorption rates are similar or even higher than those from milled nanomaterials. Also, loading/unloading processes are reproducible by at least 1000 cycles markedly exceeding the stability of milled nanomaterials. Controlled SPD processing of Shape Memory Alloys (SMAs) allows to affect not only the SME range but also their superelasticity, revocery stress and cyclic stability, paired with superior ductility and enhanced UTS. SPD processing of ferromagnetic SMAs has a strong impact on the kinetics of the martensitic phase transformation as well. Recently, SPD-mediated nanocrystallization reached record values for the efficiency of thermoelectric materials ('figure of merit ZT'). For p- and n-type skutterudites, HPT yields a marked reduction in grain size and increase in dislocation density. This decreases the thermal conductivity by 40% compared to conventionally milled skutterudites, and increases ZT by at least a factor 2. Work supported by FWF Austrian Science Fund under project S 10403