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

• Applicants: Professor Dr.-Ing. Christian Haase; Professor Dr.-Ing. Johannes Henrich Schleifenbaum
• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 495170078

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).

• DFG Programme: Research Grants