Kaka Ma

The low deposition efficiency in directed energy deposition (DED) has prompted the reuse of powders that do not fuse to the builds to make additive manufacturing more sustainable. It is unknown, however, how the properties of the powder and deposited parts change as powders are continuously reused. In this study, AlSi10Mg was investigated for five deposition cycles in DED. Exposing AlSi10Mg powder to DED conditions changes the morphology, size, and flowability. The mechanical properties of AlSi10Mg DED parts decreased after the feedstock powder was reused one time. Notably, no additional significant changes were observed when the powder was further reused.

The quality of parts fabricated with additive manufacturing is influenced by the flowability of the feedstock particles, which is the result of many factors, including chemistry (e.g., true density, the presence of surface oxides, and impurities), morphology (e.g., particle shape and the presence of satellites), and particle size distribution. This work investigates the relationship between powder characteristics and flow behavior of different powders using three flowability testing methods. Six powders of two compositions (316L stainless steel and AlSi10Mg), made using two different methods (gas‐ and water‐atomization), are investigated to rationalize the effect of powder chemistry and morphology on flow behavior. The results show that the true density of the powders can influence several flowability metrics. In addition, aspect ratio strongly influences the initiation of flow from a static condition, whereas average particle size strongly dictates the ease of maintaining that flow.