Dresden 2014 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Electron Microscopy I - Nanomaterials

MM 23.3: Talk

Tuesday, April 1, 2014, 10:45–11:00, IFW D

Nucleation of embedded Pb nanoparticles in an Al(Ga) matrix — •Anna Moros¹, Sorin Lazar², Harald Rösner¹, Peter Schlossmacher², and Gerhard Wilde¹ — ¹Institute of Materials Physics, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany — ²FEI Company, Achtseweg Noord 5, 5600 KA Eindhoven, The Netherlands

Undercooling of the liquid phase is often observed for most liquid pure materials. This indicates the existence of a large energy barrier to nucleate the solid phase. Heterogeneous nucleation at interfaces is generally favoured, since the nucleation barrier is reduced due to pre-existing catalytic substrates. Confined systems such as nanometer-sized particles embedded in a matrix have large specific interface areas that might possibly act as heterogeneous nucleation sites during solidification upon cooling, specifically since both, Pb and AlGa crystallize in fcc structure. In the present work, nanoscaled Pb inclusions embedded in AlGa matrices were processed by melt spinning technique. Various Ga quantities were alloyed into the matrix, since Ga is miscible with Al and immiscible with Pb. By means of differential scanning calorimetry, large undercoolings of Pb nanoparticles in (Al99-xGax)Pb1 alloys were observed that increased with increasing amounts of Ga. At the same time, nanoscale chemical analyses using the SuperX detector implemented in a FEI Titan 60-300 microscope were performed and Ga segregation at the interfaces of the embedded Pb nanoparticles with AlGa-matrix was observed. In this contribution, the correlation between the segregation of Ga at the particle-matrix interface and the resulting undercooling of the nanoscaled Pb particles will be discussed.