Mechanism of rapidly solidified satellites formation in gas atomized powders: Simulation and characterization

Abstract

It has been generally recognized that satellites deteriorate significantly the uniformity and stability of powder spreading in additive manufacturing (AM). Therefore, it is crucial to investigate the mechanism of satellites formation and the microstructure of collision region. In this study, the turbulent flow of gas was numerically simulated in an atomizing chamber using the shear stress transport k-ω (SST k-ω) model. Then, the Taylor analogy breakup (TAB) model and the discrete phase model (DPM) were used to analyze the breakup process of the secondary atomization of superalloy droplets which formed during the primary atomization. Meanwhile, the impact mechanism of the recirculation zone on the satellites was investigated in the atomization chamber. Scanning electron microscopy (SEM) was used to characterize the morphology and cross-sectional microstructure in the collision region of the satellites. Three collision types of satellites were identified. The findings of this study enhance the understanding of the mechanism of satellites formation and provide technical insight into the control and elimination of satellites in argon atomization (AA).