A lattice Boltzmann – phase field model with sharp-interface tracking has been developed to investigate dynamics of dendritic growth and sedimentation during the non-equilibrium solidification of alloys. The validation of the proposed model is performed through comparative analysis with benchmark phenomena including drafting-kissing-tumbling interactions in two- and three-particle systems, as well as verification against the continuous growth model. Comparative studies with the multi-phase field approach demonstrate that the present model maintains quantitative accuracy while achieving significant computational efficiency improvements. Subsequent simulations focus on dendritic morphology transitions and primary dendritic arm spacing (PDAS) evolution, revealing that velocity-dependent solute partitioning and its influence on constitutional undercooling critically determine both morphological classification and PDAS characteristics. The model further enables systematic investigation of microstructural evolution and solute segregation during rapid solidification processes. Results demonstrate that free dendritic motion under non-equilibrium conditions induces profound modifications in microstructural development and segregation patterns. This study demonstrates the present framework's exceptional capability for simulating complex dendritic growth and microstructure evolution across diverse solidification regimes, while traditional methods often struggle with numerical stability and computational costs. The present model provides valuable insights into mechanism of microstructure formation and solute redistribution in rapid solidification of alloys.

Dendritic growth, Lattice Boltzmann, Phase field, Rapid solidification, Sedimentation