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

学院早期职业发展(Career)补助金支持旨在了解通过同轴送丝-送粉激光定向能量沉积(DED)巩固的金属部件中的工艺-结构-性能关系的基础研究。这项技术提供了使用粉末和线材原料分层建造和修复零件的机会。线材原料需要很高的激光能量来熔化，并可能形成不稳定的熔池，从而降低加工性。相反，粉末颗粒更小，具有更高的表面积，更容易熔化和熔化，降低了不稳定性。本研究项目综合粉末和线材沉积的优点--粉末改善的加工性能和线材较高的沉积速度--建立了同轴送丝-送粉激光定向能量沉积的制造新范式。由此产生的知识使线基添加剂制造得以更广泛地采用，从而有可能以更低的成本和材料浪费制造用于发电、推进和空间探索的健全的大型部件。因此，这项研究增强了美国的制造业、竞争力和经济。此外，这项研究还得到了教育和外展倡议的补充，这些倡议使未来的工程师和科学家能够在实现专业卓越的同时优先考虑个人福祉。该项目提供全面的专业和领导力培训，促进战略网络机会，并帮助个人做出明智的职业选择。本研究的具体目标是揭示同轴送丝-送粉激光定向能量沉积(DED)金属的工艺、组织和性能之间关系的基本机制。在竣工条件下，DED使用线材或粉末原料制造的零件的根本区别在于激光与材料的相互作用、熔化和凝固现象，以及整体的块体行为。因此，该项目的研究目标包括：(1)比较同轴送丝送粉过程与单一送粉和送丝过程中的沉积形成；(2)评估熔池的演变并量化关键的微观结构特征；(3)建立拉伸强化机制与各种送丝比之间的关联。通过追求这些研究目标，该项目旨在解决基本问题，包括：(I)添加粉末对线材DED的加工性的影响，例如降低瑞利-高原熔体不稳定性；(Ii)粉末颗粒在影响熔池形状和凝固微观组织发展中所起的特殊作用；以及(Iii)由于添加粉末而导致的个别拉伸强化机制的变化。从这些调查中获得的结果为同轴送丝送粉激光DED的机械理解提供了重要的见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.