<p>Investigations on the impact of fabrication path planning in directed energy deposition via interlayer dwell time have revealed significant improvements in the mechanical properties of the solidified material. However, the correlation between these improvements and microstructural phenomena during melt-pool solidification remains largely unexplored. As the size of the component increases, interlayer dwell time becomes more critical, as it can alter the cooling rate and help mitigate issues related to excessive heat buildup in the part. In this work, we characterize the impact of increasing interlayer dwell times on the resulting microstructure features, solute segregation, and solidification cracking. We use various modeling techniques in cooperation, including thermo-mechanical, thermo-fluid, finite difference Monte Carlo, phase-field, and analytical models to simulate the grain and dendritic growth, solute segregation, Laves phase formation, and cracking behavior during melt-pool solidification and examine their role in properties improvement in an Inconel 718 alloy. Our findings indicate that reducing interlayer dwell time can result in coarse dendritic structures that solidify primarily in the build direction due to low cooling rates and thermal gradients. In contrast, longer dwell times produce tilted dendrites driven by higher cooling rates and thermal gradients. The coarse dendritic structures create wider and longer liquid channels between the dendrite arms, which increases Nb segregation and favors the formation of detrimental Laves phase during terminal solidification, subsequently increasing the susceptibility to solidification cracking in the mushy zone. The numerical results are directly compared against experimental measurements with reasonable agreement.</p> Graphical Abstract <p></p>