Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Poster Session
MM 34.40: Poster
Dienstag, 1. April 2014, 18:00–20:00, P4
Dependence of accessible undercooling on prior liquid overheating by differential fast scanning calorimeter — •Bin Yang1, John H. Perepezko2, Jürn W. P. Schmelzer1, Yulai Gao3, and Christoph Schick1 — 1Institute of Physics, University of Rostock, Wismarsche Str. 43-45, 18051 Rostock, Germany — 2Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, WI 53706, USA — 3School of Materials Science and Engineering, Shanghai University, Shanghai 200072, P.R. China
The dependence of accessible undercooling on prior overheating of a pure tin single micron-sized droplet was studied by differential fast scanning calorimetry (DFSC) with cooling rates from 500 to 10,000 K/s. It is observed experimentally that (i) the degree of undercooling increases first gradually with increasing of prior overheating and reaches then an undercooling plateau; (ii) the accessible undercooling increases initially with increasing cooling rate. However, above a certain cooling rate the accessible undercooling decreases strongly with increasing cooling rate. For overheating levels above that for the onset of the undercooling plateau the undercooling increases with increasing cooling rate. These observed unusual behavior is successfully explained by heterogeneous nucleation in cavities. This mechanism can possibly also describe nucleation in other similar rapid solidi*cation processes.