A COUPLED FINITE DIFFERENCE-LATTICE BOLTZMANN-BASED PHASE FIELD MODEL FOR DENDRITIC EVOLUTION DURING METAL ADDITIVE MANUFACTURING

Predicting the microstructural evolution of various alloys is key in obtaining tailored macroscopic properties of additively manufactured metal parts. We propose a novel finite difference - lattice Boltzmann method (FD-LB) based phase field model (PFM) to simulate solidification dynamics and dendritic growth during additive manufacturing. The model considers the phase-field evolution, temperature, and species fields, as well as the fluid flow in the liquid phase. The applicability and accuracy of the FD-LB PFM is verified with several previous numerical studies in the literature. The model is then applied to simulate the dendritic growth in two realistic alloys: (1) Al-3.0wt%Cu binary alloy and (2) aluminum alloy A356. A single seed of Al-3.0wt%Cu alloy is simulated under representative solidification parameters, while the aluminum alloy A356 is studied with various temperature gradients to determine the sensitivity on the dendritic growth speed, arm spacing, and overall morphological evolution. This work can serve as an intermediate framework in the prediction and control of micro- and macro-structural properties in metallic additive manufacturing.