Investigation of the influence of powder blends on production and materials technology aspects in Laser Powder Bed Fusion

增材制造是实现功能部件个性化和资源节约型生产的关键技术。最重要的增材制造工艺之一是激光粉末床融合（LPBF），它允许在粉末床中逐层生产金属部件。然而，目前由于缺乏适合于LPBF的材料，LPBF技术的潜力还不能得到充分的发挥。目前，主要使用为常规铸造或锻造工艺开发的材料，如1.4404、AlSi10Mg、Ti6Al4V或Inconel 718。工艺固有条件，如LPBF中极高的加热和冷却速率（约为1 / 4）。10^6 K/s)，尚未被专门开发和用于新材料的开发。因此，必须设计新的方法，以便灵活和有效地开发新的LPBF材料。通过混合不同的预合金和/或元素粉末来生产和定制合金代表了一种新的方法。混合粉末可以快速灵活地适应合金成分，而不需要单独的粉末雾化。在前期工作中，已经证明了粉末共混物在LPBF工艺中通过工件的化学成分来调节机械性能的适用性。然而，沿着LPBF工艺链（粉末共混-涂层-熔化-凝固）对粉末共混物的行为进行基础研究以及化学等效预合金粉末的比较是必要的。然而，当使用粉末混合物时，会出现挑战（例如某些类型的颗粒不完全熔化），特别是由于单个粉末类型的物理性质（例如密度，吸收系数）以及粉末颗粒的大小和形态的差异。为了验证粉末共混物在合金开发中的适用性，这些差异以及在LPBF工艺链的各个工艺步骤中可能发生的粉末偏析对材料的微观结构、化学均匀性和机械性能的影响仍需要系统地研究和了解。目前，粉末性能对粉末共混过程和工件性能的影响尚未得到深入研究。这一知识差距将通过这里申请的项目来弥补，并将与最先进的技术（使用预合金粉末）进行比较。

Additive manufacturing (AM) represents a key technology for the individualized and resource-efficient production of functional components. One of the most important AM processes is Laser Powder Bed Fusion (LPBF), which allows the layer-by-layer production of metallic components in a powder bed. At present, however, the potential of LPBF technology cannot be fully exploited due to the lack of materials suitable for LPBF. Currently, materials developed for conventional casting or forging processes, such as 1.4404, AlSi10Mg, Ti6Al4V or Inconel 718, are mostly used. Process-inherent conditions, such as extremely high heating and cooling rates in LPBF (approx. 10^6 K/s), are not yet specifically exploited and used in the development of new materials. Consequently, new approaches must be devised to enable agile and efficient development of new LPBF materials. Alloy production and alloy customization by mixing different pre-alloyed and/or elemental powders represents a new approach. Mixing of powders allows fast and flexible adaptation of the alloy composition without the need for separate powder atomizations. In preliminary works, the applicability of powder blends in the LPBF process for adjusting the mechanical properties via the chemical composition of workpieces has been demonstrated. however, fundamental investigations of the behavior of powder blends along the LPBF process chain (powder blending - coating - melting - solidification) and the comparison of chemically equivalent pre-alloyed powders are necessary. However, challenges (e.g. incomplete melting of certain types of particles) arise when using powder blends, due in particular to differences in the physical properties of the individual powder types (e.g. density, absorption coefficient) and the size and morphology of the powder particles. To validate the applicability of powder blends for alloy development, the effects of these differences and any segregation of powders that may occur in individual process steps along the LPBF process chain on microstructure, chemical homogeneity and mechanical properties of the material still need to be systematically investigated and understood. At present, the influence of powder properties on process and resulting workpiece properties in powder blends is unexplored. This knowledge gap is to be closed by the project applied for here, and a comparison is to be made with the state of the art (use of pre-alloyed powders).