From the planar-front solidification process under purely diffusive conditions key parameters, such as diffusion coefficients and the partition coefficients can be derived. In this paper a procedure is proposed to deduce the values of these thermophysical parameters from the analysis of solidification experiments. The data considered here were obtained during the first microgravity flight of the Mephisto experiment, as the procedure can only be applied when mass transport is purely diffusive. This is often impossible on earth due to unavoidable convective movements, but can be achieved in space. From the solute profile in front of the quenched interface values for the diffusion coefficient have been derived. The absolute thermopower of solid Sn- 0.5at%Bi is determined as -2.1 microvolts/K (at 227 deg C). The results of a numerical modelling of the evolution of the concentration profile and the thermoelectric signal during the initial and final transient of a planar front solidification was found to be in good agreement with the experimental results.
On the measurements of thermophysical properties during planar front solidification of an Sn-Bi alloy in microgravity: Results of the Mephisto-USMP1 experiments
Über die Messungen der thermophysikalischen Eigenschaften bei der ebenen Erstarrung einer Sn-Bi-Legierung unter Mikrogravitation: Ergebnisse der Mephisto-USMP1 Experimente
Acta Materialia ; 44 , 12 ; 4899-4907
1996
9 Seiten, 6 Bilder, 2 Tabellen, 22 Quellen
Article (Journal)
English
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