A novel numerical model of dendrite evolution/solute redistribution during columnar freezing
Conference
·
OSTI ID:227780
- Univ. of Wales, Swansea (United Kingdom)
A 2D microscopic finite difference model has been developed for simulating dendrite evolution/solute redistribution during steady-state columnar growth in binary alloys. Directional freezing proceeds along the length of a rectangular domain under prescribed conditions of temperature gradient and rate of isotherm movement. As freezing proceeds, a branched dendrite morphology naturally evolves and coarsens. Solidification is accompanied by solute rejection (assuming a partition coefficient less than unity), solute diffusion in the liquid and back diffusion of solute into the solid. The model differs significantly from previously reported 1D numerical models of microsegregation between two adjacent dendrite arms which are assumed to be plate shaped. Models of the latter type require an empirical expression to allow for dendrite arm coarsening. These expressions take no account of the continuously changing dendrite morphology during coarsening or the mechanism of coarsening and are therefore unable to truly reflect the influence of this transient phenomenon on solute redistribution. The present model has been used to predict the volume percentages of non-equilibrium eutectic arising in Al-Cu alloys and to compare these percentages with experimentally observed values.
- OSTI ID:
- 227780
- Report Number(s):
- CONF-9509118--; ISBN 0-87339-297-3
- Country of Publication:
- United States
- Language:
- English
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