Influence of AlSi10Mg particles microstructure on heat conduction during additive manufacturing

Powder-based metallic additive manufacturing (AM) technology is opening new avenues to fabricate highly complex components from metallic powders. However, most of the powder-scale modeling methods are limited to single track process and ideal particle microstructure. Nevertheless, the presence of hollow particles significantly influences the heat conduction during AM processing and experimental quantification of the heat conduction between hollow particles is extremely challenging. Herein, we have used X-ray micro-computed tomography (μCT) to reconstruct 3D structures of AlSi10Mg particles. The morphology, location and distribution of intact and hollow particles are studied to analyze their role in AM processing. Based on X-ray tomography images, two 3D image-based finite element models of statistically representative particles with imperfect geometry are reconstructed and compared to simulate the thermal conduction in the powder bed. Simulation results shows that thermal conduction is governed not only by cell topology but also by cavities in particles induced by powder production. The calculation results are consistent with the Serial-Parallel Model, which is based on the reconstruction geometry model and statistical results. The results reveal that the presence of cavities in particles significantly influences the thermal conduction and, consequently, reduces the sintered density during selective laser sintering (SLS).