The Phase I research objective is to demonstrate the feasibility of optimizing gas flow for producing defect-free repair of structural metal components using Directed Energy Deposition (DED) Additive Manufacturing (AM). Insight into the multi-physics gas interaction with metal fusion and the causality of gas-induced defect formation in DED repair will be developed using an Integrated Computational Materials Engineering (ICME) modeling framework. The gas flow model and the formation of nozzle debris due to spatter and ricochet particles will be calibrated and validated using gas velocity measurements and the in-situ layer-by-layer sensing of powder flow and top surface topology during deposition experiments. The nozzle debris mass and the geometry of melt pool formation will be used as objective functions in the ICME modeling to fine-tune the gas flow and DED processing parameters, respectively. Defect mitigation will be validated using metallography. Phase I Option will extend the ICME modeling framework, in-situ sensing, and validation experiments to Laser Powder Bed Fusion (LPBF). Phase II will demonstrate a prototype of an ICME modeling framework for DED and LPBF to fine-tune gas flow, mitigate build defects, reduce surface roughness, and enhance mechanical properties. The build material will be alloy Ti-6Al-4V.
