Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 12: Nanostructured Materials IV

MM 12.1: Vortrag

Montag, 25. Februar 2008, 16:45–17:00, H 0107

Thermal stability and sinterability of segregation-stabilized nanocrystalline alloys — •Lionel Kroner and Carl E. Krill III — Institut für Mikro- und Nanomaterialien, Universität Ulm, D-89081 Ulm

Although it has recently become possible to calculate the mechanical properties of nanocrystalline materials by means of computer simulation, testing these predictions experimentally has been hampered up to now by the difficulty of preparing nanocrystalline samples in bulk form. Ordinary synthesis routes result in powders or thin films, which might then be compacted to a fully dense state via the application of high pressure and temperature; however, the latter generally induces rapid grain growth, resulting in a coarse-grained final product. A potential strategy for sintering to high density without significant grain growth would be to suppress the driving force for coarsening by adding an atomic species that segregates to the grain boundaries. The effectiveness of this approach has already been demonstrated in nanocrystalline Pd alloyed with Zr [1], but the sinterability of such alloy systems remains to be investigated. We have prepared nanocrystalline Ni-Zr alloys by ball milling and examined the thermal stability and densification as a function of Zr concentration. The microstructural evolution that occurred during pressureless sintering was measured by high-temperature x-ray diffraction, and the density following compaction was determined by Archimedes’ method.
C. E. Krill III, H. Ehrhardt and R. Birringer, Z. Metallkd. 96 (2005) 1134-1141