| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Materials Research in Reduced Gravity
|
| Presentation Title |
Numerical Modeling of Columnar to Equiaxed Transition During Directional Solidification of Al-7wt%Si Alloys in Reduced Gravity |
| Author(s) |
Amirhossein Molavi Tabrizi, Chih-Hung Chen, Alain S. Karma, Kaihua Ji |
| On-Site Speaker (Planned) |
Kaihua Ji |
| Abstract Scope |
During alloy solidification, dendritic microstructures typically form with a columnar or equiaxed grain structure and often display a transition between the two grain structures. Understanding how growth conditions and nucleation parameters control this columnar-to-equiaxed transition (CET) is important since the grain structure directly affects mechanical behavior. We report the results of a numerical modeling study of the CET investigated in Al-7wt%Si samples containing grain refiners that were directionally solidified under different cooling conditions onboard the International Space Station. Modeling makes use of a 3D dendrite needle network model that resolves diffusive interactions between growing columnar and equiaxed grains on a scale much larger than the dendrite tip radius. The model predicts either a sharp CET in the case of a sudden increase in the solidification velocity and a progressive CET in the case of a continuous decrease of the temperature gradient in good agreement with experimental measurements. |
| Proceedings Inclusion? |
Planned: Publication Outside of TMS |