Dresden 2014 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 11: Microstructure and Phase Transformations II - Nucleation/Solidification

MM 11.3: Vortrag

Montag, 31. März 2014, 12:00–12:15, IFW B

Analysis of the size effect and interfacial structure on the solidification and melting behavior of embedded Bi nanoparticles — •Tae Eun Song, Martin Peterlechner, and Gerhard Wilde — Institute of material physics, Wilhelm-Klemm-Strasse, D-48149, Münster, Germany

Abstract Bi nanoparticles embedded in Zn or Al matrices were synthesized by rapid solidification and casting. The kinetics of Bi nanoparticles solidification has been examined by heating and cooling experiments in a differential scanning calorimeter (DSC). Upon heating in the DSC two Bi melting signals occur, one close to the eutectic temperature and the other at a lower temperature. Subsequent cooling leads to two solidification signals. Some Bi particles solidify at a small undercooling with a sharp exothermic peak, whereas other Bi particles solidify at a larger undercooling with a broad exothermic peak. The microstructure was analyzed by transmission electron microscopy (TEM). Cast samples show embedded Bi particles with a size larger than 80 nm and melt spun samples show embedded Bi nanoparticles with a size larger than 5 nm. The Bi nanoparticles that have an elongated and faceted morphology show an orientation relationship with the matrix. The solidification is interpreted using the classical theory of heterogeneous nucleation. Analysis of the results emphasizes the important role of the local microstructure of embedded Bi nanoparticles and of the liquid*solid interface of embedded Bi nanoparticles with matrix.