Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 34: Poster session II

MM 34.3: Poster

Dienstag, 21. März 2017, 18:30–20:30, P4

Nucleation Kinetics of deeply undercooled Germanium melts — •Manoel da Silva Pinto, Christian Simon, and Gerhard Wilde — Institut für Materialphysik - Wilhelm-Klemm Straße 10, 48149 Münster

In the classical nucleation theory the initial event of solidification is the stochastically formed metastable nuclei in the melt, which turn to be stable after exceeding the critical energy barrier. The statistical nature can be observed by the measurement of melting and solidification temperatures upon thermal cycling. By treating nucleation events as an inhomogeneous Poisson process, it is possible to estimate the nucleation rates from the undercooling values. Even an estimation of the interfacial energy applying classical nucleation theory is possible. The present work studies the nucleation of liquid germanium and estimates the nucleation rate and interface energy. We use differential thermal analysis to obtain sufficient big and accurate data sets. To avoid external nucleants and expel possible metal oxides from the sample, an inorganic glass is used as a fluxing agent and embedding medium.* A large undercooling is observed in pure germanium. The Gibbs free energy and the kinetic prefactor suggest a nucleation of heterogeneous nature. The geometric factor can be estimated and compared to the suggested value for this lattice system.