On the fabrication of a FeCrAlMoTiNi multi-principal element alloy by material extrusion additive manufacturing

• Fe 1.5 Cr 1 Al 0.75 Mo 0.1 Ti 0.1 Ni 0.25 MPEA has been successfully processed by MEX. • Highly loaded feedstock affects the diffusion-control event in solvent debinding. • MEX-processed green parts require slow heating rate during thermal debinding. • Highly dense sintered parts display homogeneous BCC/B2 isotropic microstructures. • Sintering temperature is a key parameter to control undesired elemental segregation. Multi-principal element alloys (MPEAs) are a new paradigm in alloy design with promising applications. Their composition can be tailored to meet specific goals but their final microstructure, and thus properties, highly depends on the chosen processing technique. Material Extrusion Additive Manufacturing (MEX) provides freedom in geometry selection and maximum use and reuse of the starting materials. It also produces homogeneous and isotropic microstructures with low residual stress. These assets make MEX a great candidate for MPEAs processing, however the research on the microstructures obtained with this technique are lacking. This work concerns the fabrication of a promising FeCrAlMoTiNi MPEA by MEX. An in-depth study on the different stages of this technique has been carried out from the metal/polymer feedstock fabrication and characterization to the optimization of the binder elimination steps, finishing with a study on the effect of sintering temperature on the resulting microstructures. The results show that MEX is a promising candidate to produce highly dense MPEAs parts with homogeneous microstructures and that the sintering temperature selection is key to avoid segregation of elements during fabrication.