Dresden 2003 – scientific programme

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M: Metallphysik

M 34: Phasenumwandlungen I

M 34.2: Talk

Thursday, March 27, 2003, 10:30–10:45, IFW A

Multiscale Modelling of Equiaxed Solidification into a Supercooled MeltMultiscale Modelling of Equiaxed Solidification into a Supercooled Melt — •Ingo Steinbach and Hermann-Josef Diepers — Access e.V. Intzestr. 5 52072 Aachen

A mesoscopic simulation model is presented to predict the kinetics of equiaxed alloy solidification after nucleation in a supercooled melt. The model is an extension of a previous model for equiaxed solidification of a pure melt, that was successfully applied to simulate the growth kinetics of ultrapure succinonitrile dendrites. The new alloy model uses the analytical expression of the growth kinetics of a single dendrite tip (microscopic scale) in combination with numerical calculation of heat balance in the multi phase region (mesoscopic scale) and thermal diffusion (macroscopic scale). The new aspect of the model is the comprehensive treatment of the growth kinetics on the different lengthscales by applying the stagnant film approximation of the Ivantsov solution. This allows to close the mathematical problem of thermosolutal balance without resolving the complex dendritic structure of the equiaxed grain.

The model is verified against microgravity experiments using the pure substance succinonitrile (SCN) and is further applied to the transient growth and interaction of equiaxed dendrites grown in the binary alloy succinonitrile-acetone (SCN-acetone).