Characterizing the Dynamics of the Laser Metal Deposition Additive Manufacturing Process

激光金属沉积（LMD），也称为吹制粉末直接激光沉积，是一种重要的增材制造技术，用于生产航空航天、汽车、生物医学和国防工业中各种应用的定制和功能分级部件。尽管目前对LMD技术的研究和开发的投资正在迅速增长，但在生产具有可重复和可预测性能的金属零件方面仍然存在重大挑战。该研究项目将详细探索LMD的过程;确定缺陷形成和零件质量不确定性的来源;并为在LMD制造中创建可重复和可预测的属性奠定基础。 该研究项目包括丰富的教育和推广部分，这将为本科生和研究生提供接触增材制造的机会。将开发一个电子学习模块，以传播该项目获得的数据和知识。这些知识使建模人员能够改进和验证模型和仿真工具。因此，这项研究将提高美国工业的竞争力，支持国内经济增长和国防。这项研究的总体目标是表征LMD过程的动态下的表面的熔池在一个高的空间和时间分辨率，以了解LMD过程的基本机制。该研究项目的具体目标是表征：（1）熔池形成和演化的动力学，以及熔池内的熔体流动;（2）孔形成和演化的动力学;（3）在具有不同成分的吹制粉末期间的材料混合行为;以及（4）LMD期间的凝固过程的动力学。研究方法使用原位高速高能和高分辨率同步加速器x射线成像和高速高能x射线衍射。该项目将大大推进对LMD增材制造工艺的基本理解。将揭示LMD过程中的熔池、孔隙、材料混合和凝固的动力学。该奖项反映了NSF的法定使命，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。

Laser metal deposition (LMD), also called blown-powder direct laser deposition, is an important additive manufacturing technique for producing customized and functionally-graded parts for a variety of applications in the aerospace, automobile, biomedical and defense industries. Even though investment in current research in, and development of, LMD technology is growing quickly, significant challenges remain in production of metal parts with repeatable and predictable properties. This research project will explore in detail the processes of LMD; identify the sources of defect formation and part quality uncertainties; and lay the groundwork for creating repeatable and predictable properties in LMD manufacturing. The research project includes rich educational and outreach components, which will provide undergraduate and graduate students with exposure to additive manufacturing. An e-Learning module will be developed to disseminate the data and knowledge obtained by this project. The knowledge allow modelers to improve and validate models and simulation tools. This research will therefore advance competitiveness of U.S. industry, supporting domestic economic growth and national defense.The overall objective of this research is to characterize the dynamics of the LMD process beneath the surface of the melt pool at a high spatial and temporal resolution to understand the fundamental mechanisms of the LMD process. The specific objectives of this research project are to characterize: (1) the dynamics of melt pool formation and evolution, and melt flow within the melt pool; (2) the dynamics of pore formation and evolution; (3) the material mixing behavior during blowing powders with different compositions; and (4) the dynamics of the solidification process during LMD. The research approach uses in-situ high-speed high-energy and high-resolution synchrotron x-ray imaging and high-speed high-energy x-ray diffraction. This project will significantly advance the fundamental understanding of the LMD additive manufacturing process. The dynamics of melt pool, pore, material mixing, and solidification during the LMD process will be revealed. The fundamental mechanisms of melting, mixing, defects formation, and microstructure evolution during LMD process will be unraveled.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.