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

加法制造是实现功能部件个性化、资源节约化生产的关键技术。最重要的AM工艺之一是激光粉床融合(LPBF)，它允许在粉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技术的潜力还没有得到充分的发挥。目前，用于传统铸造或锻造工艺的材料主要是1.4404、AlSi10 Mg、Ti6Al4V或Inconel718。工艺-固有条件，如LPBF中极高的加热和冷却速度(约10^6 K/S)，尚未在新材料开发中具体开发和利用。因此，必须设计新的方法来实现新的LPBF材料的敏捷和高效的开发。通过混合不同的预合金粉和/或元素粉进行合金生产和合金定制是一种新的方法。粉末混合允许快速灵活地调整合金成分，而不需要单独的粉末雾化。在初步工作中，已经证明了LPBF工艺中的粉末混合物可以通过工件的化学成分来调整机械性能。然而，有必要对粉末混合物沿LPBF过程链(粉末混合-涂层-熔化-凝固)的行为进行基础研究，并比较化学等效的预合金粉末。然而，当使用粉末混合物时，尤其是由于各种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，出现了挑战(例如，某些类型的颗粒不完全熔化)。为了验证粉末混合物在合金开发中的适用性，还需要系统地研究和了解这些差异以及在LPBF工艺链的各个工艺步骤中可能出现的粉末偏析对材料的微观结构、化学均匀度和力学性能的影响。目前，粉末混合工艺中粉末性能对加工过程和所产生的零件性能的影响还没有被探讨。这一知识差距将通过这里申请的项目来弥合，并将与最先进的技术(使用预合金粉)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).