|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Frontiers in Solidification: An MPMD Symposium in Honor of Michel Rappaz
||Simulation of Crystal Sedimentation and Viscoplastic Behavior of Sedimented Equiaxed Mushy Zones
||Andreas Ludwig, Alexander Vakhrushev, Menghuai Wu, Tobias Holzmann, Abdellah Kharicha
|On-Site Speaker (Planned)
During solidification of castings, equiaxed crystals that form sink downwards, sediment and form a packed bed. The behavior of separated moving crystals can be described by a submerge object approach, whereas the viscoplastic behavior of a semi-solid slurry follows a volume-averaged viscoplastic constitutive equation. A two-phase Eulerian-Eulerian volume-averaging approach is used to combine both flow regimes. The transition happens at a certain solid volume fraction, the so-called coherency limit. Starting with a given distribution of crystals, sedimentation and packing of the crystals is described. It is shown that draining of the packed bed can be uneven, which might lead to areas with more crystals which sometimes collapse when the amount of solid exceeds some limit. It is demonstrated how sensitive the model results depend on the considered crystal diameters and on the assumed value for the coherency limit.