On the preparation and characterization of AlSi12-graphene powder for powder bed fusion additive manufacturing applications

This study investigates the possibility of using dry mechanical mixing techniques to prepare ideal composite powders for L-PBF applications. For this purpose, two AlSi12-reinforced composite powders with 0.5 and 1 wt% graphene were prepared by ball milling and regular mixing processes. The powder attributes (size, size distribution and shape), behaviors (absorptivity, packing density, and flowability), relative humidity, and O/C/H content of the composite powders were quantitatively assessed after mixing and compared to those of monolithic AlSi12. The attachment of the graphene particles and their evolutions during each mixing technique were qualitatively investigated. The quality of the graphene powder before and after mixing was studied by Raman spectroscopy, and the nature of the carbonaceous constituent in the composite powders was identified based on the Raman peak positions, shapes and relative intensities. The results of this study prove that only through ball milling ideal composite powders for the L-PBF applications can be achieved.