Abstract
A meso-scale front-tracking model (FTM) of nonequilibrium binary alloy dendritic solidification has been extended to incorporate Kurz, Giovanola, and Trivedi (KGT) dendrite kinetics and a Scheil solidification path. Model validation via comparison with thermocouple measurements from a solidification experiment, in which natural convection is limited by design, is presented. Via solution of the flow field due to natural thermal buoyancy, it is shown that resultant liquid-phase convection creates conditions in which equiaxed solidification is favored. Comparison with simulations in which casting solidification is diffusion controlled show that natural convection has greatest effect at intermediate times, but that at early and late stages of columnar solidification, the differences are relatively small. It is, however, during the time of greatest divergence between the simulations that the authors' predictive index for equiaxed zone formation is enhanced most by convection. Finally, the columnar-to-equiaxed transition is directly simulated, in directional solidification controlled by diffusion.
| Original language | English |
|---|---|
| Pages (from-to) | 1476-1484 |
| Number of pages | 9 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 38 A |
| Issue number | 7 |
| DOIs | |
| Publication status | Published (in print/issue) - 1 Jul 2007 |
Funding
The authors are grateful to the European Space Agency for funding via the CETSOL (columnar-equiaxed transition in solidification processing) Microgravity Applications Promotion project (Contract No. CCN002-14313/01/NL/SH). We also thank Mr. M. Seredynski, Warsaw University of Technology, for performing some of the calculations.