Interaction of gas bubbles and dendrite interfaces during directional solidification: Modeling and experiment

• • A 2D multiphase CA–FD–LB model is adapted and validated for simulating bubble dendrite interactions during solidification. • • Morphological evolution including bubble engulfment and entrapment is reproduced with quantitative solute field analysis. • • Effects of bubble size and position on dendrite spacing adjustment are clarified through simulation and in situ observation. • • Simulation results show good spatial–temporal agreement with experiments, confirming the model’s predictive capability for solidification scenarios. A two-dimensional (2-D) cellular automaton–finite difference–lattice Boltzmann (CA–FD–LB) model, combined with in situ directional solidification experiments using a transparent SCN-ACE alloy, is employed to investigate gas bubble–dendrite interactions. The model couples CA for dendrite growth, FD for solute diffusion, and the Shan–Chen LB method for multiphase fluid dynamics. Validation tests, including Laplace’s law and contact angle predictions, confirm the model’s reliability. Simulations and experiments under comparable solidification conditions systematically explore two key interaction modes: bubble engulfment and entrapment. Results show that bubbles act as solute sinks, locally altering the solute field and accelerating solid envelope formation. Quantitative analyses reveal that larger bubbles induce stronger solute redistribution, suppress side branches, and promote dendrite spacing adjustment by eliminating and regenerating dendrites. The relative position between the bubble and dendrite tip also significantly affects interaction morphology. Furthermore, multibubble–multidendrite interactions are modeled to reflect complex real conditions. The simulated dendrite evolution, solute field variation, and interface morphology show good agreement with experimental observations, demonstrating the model’s capability to capture realistic phase interactions and to provide insights into the mechanism of bubble-induced perturbations in solidification microstructures.