Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 35: Poster Session II

MM 35.18: Poster

Mittwoch, 25. März 2009, 16:30–18:30, P4

Influence of Ga on the melting behaviour of Pb nanoparticles — •Anna Moros, Harald Rösner, and Gerhald Wilde — WWU Münster, Institute of material physics

In recent years there have been many analyses of the melting of Pb nanoparticles embedded in Al, but the corresponding mechanism of melting is still not completely understood. The current research project analyzes Al-1at%Pb samples, which are prepared by melt-spinning. The melting behaviour of Pb nanoparticles was determined by differential scanning calorimetry. In contrast to findings for free particles and in contradiction to many models of size-dependent melting, it was found that the particles melted at 10-30 K above the melting point of the bulk material. Analyses of TEM-images yielded a bimodal size distribution with most of the small particles in the size range between 2-20 nm. The resolved lattice mismatch between the faceted Pb nanoparticles and the matrix is suggested to be the key to understanding the melting behaviour. What happens if the matrix lattice changes due to alloying of other components? For our project we chose Gallium since it is miscible with Al, but immiscible with Pb. First results were obtained on 6at% Ga and 1at%Pb samples. The results by DSC and TEM are discussed with respect to the impact of the lattice mismatch between particles and matrix on the melting point variation.