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

该学院早期职业发展（Career）基金支持基础研究，旨在了解通过同轴线进给-粉末进给激光定向能沉积（DED）巩固的金属部件的加工-结构-性能关系。这种技术提供了使用粉末和线材给料分层构建和修复零件的机会。钢丝原料需要高激光能量来熔化，并且可能形成不稳定的熔池，从而降低可加工性。相反，粉末颗粒更小，具有更高的表面积，更容易熔化和融合，不稳定性降低。本研究项目结合粉末和线材沉积的优点——粉末可加工性的提高和线材沉积速率的提高——建立了同轴送丝-送粉激光定向能沉积的新制造模式。由此产生的知识使基于线材的增材制造得到更广泛的应用，有可能以降低成本和材料浪费的方式制造用于发电、推进和太空探索的大型部件。因此，这项研究可以增强美国的制造业、竞争力和经济。此外，这项研究还辅以教育和推广活动，使未来的工程师和科学家能够在优先考虑个人福祉的同时实现专业卓越。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金属同轴线进给-粉末进给激光定向能沉积（DED）过程中加工、微观结构和性能之间关系的基本机制。在建成条件下使用线材或粉末原料的DED制造的部件的根本区别是激光材料相互作用，熔化和凝固现象以及整体整体行为。因此，本项目的研究目标包括：(i)比较同轴线材进料-粉末进料过程与单一粉末和线材进料过程中的沉积物形成；（ii）评估熔池的演变并量化关键的微观结构特征；（iii）建立拉伸强化机制与不同钢丝粉料进料比之间的相关性。通过追求这些研究目标，该项目旨在解决基本问题，包括：(i)粉末添加对线材DED可加工性的影响，如减少瑞利高原熔体不稳定性；（二）粉末颗粒在影响熔池形状和凝固微观结构发展方面所起的特殊作用；（三）粉末掺入导致的单个拉伸强化机制的变化。从这些研究中获得的结果为同轴线进给-粉末进给激光DED的机理理解提供了重要的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.