CAREER: Understanding Processing-Structure-Property Relationships in Co-Axial Wire-Feed, Powder-Feed Laser Directed Energy Deposition

This Faculty Early Career Development (CAREER) grant supports fundamental research aimed at understanding the processing-structure-property relationships in metallic components consolidated through co-axial wire feed-powder feed laser directed energy deposition (DED). This technique offers the opportunity to construct and repair parts in layers using both powder and wire feedstocks. Wire feedstocks necessitate high laser energy for melting and may form unstable melt pools resulting in reduced processability. Conversely, powder particles, being smaller and possessing a higher surface area, are easier to melt and fuse with reduced instability. This research project integrates the advantages of both powder and wire deposition – powder's improved processability and wire's higher deposition rate – to establish a new manufacturing paradigm of co-axial wire feed-powder feed laser directed energy deposition. The resulting knowledge enables wider adoption of wire-based additive manufacturing, holding the potential to fabricate sound large-scale parts for power generation, propulsion, and space exploration at reduced cost and material waste. Thus, the research augments U.S. manufacturing, competitiveness, and economy. Furthermore, this research is complemented by educational and outreach initiatives that empower future engineers and scientists to achieve professional excellence while prioritizing personal well-being. The project provides comprehensive professional and leadership training, facilitates strategic networking opportunities, and assists individuals in making informed career choices.The specific goal of this research is to unveil the fundamental mechanisms governing the relationships between processing, microstructure, and properties in co-axial wire feed-powder feed laser directed energy deposition (DED) of metals. The fundamental differences in parts created by DED using wire or powder feedstocks under as-built conditions are laser-material interactions, melting and solidification phenomena, and the overall bulk behavior. Consequently, the research objectives of this project encompass: (i) comparing deposit formations in the co-axial wire feed-powder feed process with singular powder and wire feed processes; (ii) assessing the evolution of melt pools and quantifying crucial microstructural characteristics; and (iii) establishing correlations between tensile strengthening mechanisms and a spectrum of varying wire-to-powder feed ratios. By pursuing these research objectives, the project aims to address fundamental questions, including: (i) the impact of powder addition on the processability of wire DED such as reduction in Rayleigh-Plateau melt instabilities; (ii) the specific role played by powder particles in influencing the shape of melt pools and the development of solidification microstructures; and (iii) the variations in individual tensile strengthening mechanisms due to powder incorporation. The results obtained from these investigations provide critical insights into the mechanistic understanding of co-axial wire feed-powder feed laser DED.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.