Particle-Melt Pool Interactions in Multi-Material Laser Based Directed Energy Deposition

Laser based metal directed energy deposition (DED) is an additive manufacturing process that is currently on the rise in the industry. However, there is still a knowledge gap in the understanding of fundamental interactions between particles and the melt pool in the DED process and how to change the parameters to alter microstructure. This work utilized synchronized in-situ thermal and X-ray imaging to understand the anomalous behavior of molybdenum powder binding onto a Ti-6Al-4V substrate as fundamental understanding for layer-by-layer processing. Using these visual techniques, particle velocity, mass, surface energy, kinetic energy, contact area, and temperature were observed and calculated. The correlation is shown and recorded to understand the wettability of particles and why some will bounce off of the substrate while others enter the melt pool. This work will allow for the manipulation of particle-melt pool interactions in DED which will help reproduce and build better parts more efficiently