Optimization of the powder feedstock for use in Laser Powder Bed Fusion

E. Saggionetto1, A. H. Seidou1, G. Roger Vila1, O. Dedry1, F. Boschini2, J. T. Tchuindjang1, A. Mertens1

1Metallic Materials Science (MMS), Aerospace and Mechanical Engineering Dpt., University of Liège
2GREEnMat Laboratory, University of Liège


Among Additive Manufacturing (AM) technologies, Laser Powder Bed Fusion (LPBF) is a suitable technique to create near net-shape parts starting from powders. Yet the choice of metal alloy powders available in the market, especially Fe-based alloys, remain still limited. The mixing of two or more different powders is a promising way to broaden the possible choice of materials, as it allows to achieve tailored compositions. However, powders for LPBF must present appropriate rheological properties. Indeed, as the part is built layer by layer, each layer of powders is spread from the powder platform to the building platform. If the initial batch of powders is not homogeneous, both spreadability and laser - powder interaction suffer, affecting the final part quality.

This work thus focuses on the preparation of the mixture of AISI S2 tool steel and silicon carbide (SiC) powders for use in LPBF. To promote the complete dissolution of SiC within the melt pool during the LPBF process, spray dried granules of SiC nanoparticles (0.7 µm) were selected. However, these particles show an easy tendency to compact, creating agglomerates that compromise the spreadability and processability of the powders mixture. Different preparation methods have been investigated and a combination of sieving, mechanical alloying by ball milling and thermal treatment was finally selected   as it resulted in good rheological properties of the powders mixture as well as in a good quality of the final part.