3D Phase Field Modeling on Fusion and Void Formation of Triplet Metallic Powders

Laser-based additive manufacturing (AM) process is important in aerospace and biomedical industry due to the request for superior quality and liability on shape-complicated parts. However, the multiphase dynamics involved in the high temperature AM manufacturing process is complicated by for examples the interplays of spot laser heating, dynamic powder-powder interactions, melting and solidification of pure and alloy-based metallic powders, evaporation, and the strong thermal capillary flow of the molten metal. A full process simulation including a broad range of thermophysical properties can be an overwhelming task even for pure metals. We focus on quantifying the dynamic void or defect formation due to incomplete melting or fusion of three metallic powders. This is important in predicting surface defect which may lead to crack or early failure of AM produced parts. The small scale analysis based on phase field formulation has successfully characterized the dynamic coupling of three phase evolution, solid-liquid phase transition, and the thermal capillary flow driven by a fixed or scanning laser beam. The simplified analysis on the triplet powder interaction provides a primitive model for describing complicated many or hybrid powder interactions.