Gas vs. Ultrasonic Atomized AlSi10Mg Powders: Morphology, Flowability, and Discharge Behavior Using Real and In Silico Experiments

Laser powder bed fusion (LPBF), one of the most established metal additive manufacturing technologies, depends strongly on the physical, morphological, and rheological characteristics of the powder feedstock to ensure process stability, layer uniformity, and final part quality. This study compared three AlSi10Mg powders intended for LPBF: one ultrasonic-atomized powder and two gas-atomized powders from different suppliers. The powders were evaluated in the as-received condition and after exposure to high-temperature/high-humidity and high-temperature/low-humidity environments. Particle size distribution, SEM/EDS, helium pycnometry, Karl Fischer moisture analysis, apparent density, Carney funnel flow, FT4 powder rheometry, and a LAMMPS-based Carney funnel simulation were used. The ultrasonic-atomized powder showed the lowest moisture uptake (77.74 ppm after humid conditioning, compared with 386.9 and 495.7 ppm for the gas-atomized powders), fewer satellite particles, lower agglomeration, and higher apparent density. Its Carney funnel flow time remained nearly constant (8.0–8.6 s), whereas one gas-atomized powder increased from 12.2 to 15.2 s after humid exposure. FT4 measurements also indicated lower effective internal friction and wall-friction angles for the ultrasonic-atomized powder, while the gas-atomized powders exhibited greater resistance to motion and stronger sensitivity to the applied stress state. Although the powders showed broadly similar chemical composition, differences in particle size distribution, morphology, moisture sensitivity, and frictional behavior led to clear differences in flow performance. Because the powders also differed substantially in particle-size distribution, the effects attributed to atomization route are interpreted together with particle size and supplier effects rather than as route effects alone. The LAMMPS simulation remained qualitative because the modeled mass was limited to 10% of the estimated powder mass; nevertheless, it reproduced the same discharge ranking observed experimentally in the Carney funnel tests.