About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Frontiers in Solidification X
|
| Presentation Title |
Refining the Rayleigh number approach to predict the onset of freckling during solidification of multicomponent metal alloys |
| Author(s) |
Owain Houghton, Adrian Sabau, Gregory Olson |
| On-Site Speaker (Planned) |
Owain Houghton |
| Abstract Scope |
Convective instability in the semi-solid ‘mushy’ zone of solidifying alloys, which causes defects known as freckles, mesosegregates, channel or A-type segregates, is often described using criteria based on the work of Flemings or a Rayleigh number approach. These two approaches, however, do not always agree well. To unify these two approaches, we consider Flemings’ model to derive a general criterion for the onset of local remelting of the mushy zone that accounts for the conservation of solute, mass, and energy. This general criterion is used to derive the Rayleigh number (Ra) and an independent expression for the critical value (Racrit) above which freckles form. Predictions of the onset of freckling from our analytical model for Ni-based superalloys, Pn-Sn alloys and steels are compared to previous empirical studies. Discrepancies between the model and experimental results due to local flow instabilities, defects, and variations in the local solidification rate are considered. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Solidification, Process Technology, Modeling and Simulation |