Fundamental in-situ Investigations on the Changes of Particle Properties during Powder Bed Fusion of Cu-based materials using a Laser Beam, Depending on the Atmosphere and the Exposure Parameters

总体目标是对纯铜粉末粉末床熔合（PBF）过程中粒子性能变化的影响以及对激光能量耦合、微观结构形成过程和相关机械和物理性能的相关影响有一个基本的了解。本项目重点研究铜粉表面对氧的吸收，研究粉末性能的变化及其对可重复使用性的影响，以及粉末调理（回收）和暴露参数或工艺气体气氛方面必要的工艺技术调整。因此，高分辨率的原位x射线衍射实验将用于研究pbf过程中具有特定和已知性质的块状粉末，工艺气体气氛和激光束之间发生的相互作用。所获得的知识将用于制定措施（通过预氧化，回收的粉末表面的目标老化），允许再现PBF处理铜散装粉末。通过形成氧化物和沉积薄镍层的目标表面调理旨在增加激光吸收，这一方面有助于提高工艺速度，另一方面，使pbf加工具有高反射率（Cu）的材料，适用于今天通常使用的激光器（波长≈1060 nm）。还将研究熔体粘度（光滑表面和机械加工的次要后处理）是否会受到引入氧气（通过颗粒氧化，通过使用混合气体的工艺气体）的影响。上述具有高技术相关性的科学问题在一个项目联盟中得到了回答，其中包括粉末加工和粉末性能评估（HAM），微观结构表征和相关材料性能（FUW），以及用于绘制散装粉末氧化和还原动力学的原位重熔试验和老化试验（FPTUDo）。

The overarching goal is to develop a basic understanding of the influence of changes in particle properties in the Powder Bed Fusion (PBF) process of pure Cu-powder and the associated influence on the laser energy coupling, the microstructure formation process, and the associated mechanical, and physical properties. This project focuses on the absorption of oxygen by Cu-powder surfaces, investigations on the change in powder properties and their influence on reusability and the necessary process-technical adjustments concerning powder conditioning (recycling) and the exposure parameters or the process gas atmosphere. Therefore, high-resolution in-situ X-ray diffraction experiments will be carried out to investigate the interactions occurring in the PBF-process between the bulk powder with specific and well-known properties, the process gas atmosphere, and the laser beam. The knowledge gained will be used to derive measures (targeted aging of powder surfaces by pre-oxidation, recycling) which allow reproducible PBF processing of Cu-bulk powder. Targeted surface conditioning through the formation of oxides, and the deposition of thin Ni-layers is intended to increase laser absorption, which on the one hand, contributes to increasing the process speed and, on the other hand, enables the PBF-processing of materials with high reflectivity (Cu) for the lasers typically used today (wavelength ≈1060 nm). It will also be investigated whether the melt viscosity (smooth surfaces and minor post-processing by machining) can be influenced by the introduction of oxygen (by particle oxidation, via the process gas by using mixed gases) into the PBF-process. The aforementioned scientific questions with high technological relevance are answered in a project consortium, in which the competences concerning powder processing and the evaluation of powder properties (HAM), the characterization of the microstructure and the associated material properties (FUW), and the in-situ re-melting tests and aging tests for mapping the oxidation and reduction kinetics of bulk powder (FPTUDo) are available.