(V) INVITED: Non-Equilibrium Solidification and Additive Manufacturing

The morphology of grains produced during additive manufacturing is central to controlling the properties of the final build. The polycrystalline structure following additive manufacturing is examined in the limit of large interfacial velocities where there is complete solute trapping or absolute interfacial stability. A phase field model is developed that simulates the evolution of grains in three dimensions as a function of time during additive manufacturing. The advantage of the approach is that it captures the motion and rotation of trijunctions, where the solid-liquid interface and grain-boundary meet, during solidification and thus evolution of the grain morphology; it is not a rule-based model. The parameters needed for the model are derived from molecular dynamics methods such as those pioneered by M. Asta and his many collaborators. Examples of the three-dimensional calculations and the critical role of anisotropic solid-liquid interfacial mobility will be discussed.