Degradation of AlSi10Mg powder during laser based powder bed fusion processing

Knowledge concerning powder degradation during additive manufacturing (AM) processing is essential to improve the reusability of the powder in AM and hence maximize feedstock powder reuse and economy of the process. AlSi10Mg powder degradation in Concept Laser XLINE 2000R machine over the total period of 30 months was analyzed in order to understand the extent and mechanism affecting powder aging. Thereby, detailed analysis of the powder morphology, microstructure and surface chemistry was performed by SEM, TEM and XPS. The results show an increase in volume fraction of heavily oxidized spatter particles up to 3% in 30 months. XPS analysis of the powder surface chemistry indicates that powder particles are covered by uniform oxide layer, formed by Mg and Al-based oxides, average thickness of which increased from similar to 4 nm in case of the virgin powder up to about 38 nm in case of the reused for about 30 month powder, established by XPS. Analysis of the oxide characteristics were consistent with the observed oxygen content in the sampled powder. Columnar oxide scale formation on spatter particles was revealed as well, reaching up to 125 nm in thickness measured using STEM. Results of the XPS and STEM-EDX analysis of oxide composition are shown to be in agreement with the thermodynamic calculations confirming that oxide scale on sputter particles is formed by MgAl2O4 spinel and Al2O3 (corundum) oxides. (C) 2020 The Author(s). Published by Elsevier Ltd.

Automated summary

The study found that AlSi10Mg powder undergoes oxidation aging during AM processing, with the powder surface covered by a uniform oxide layer, affecting the reusability of the powder. The analysis showed an increase in volume fraction of heavily oxidized spatter particles and the formation of oxide scale on spatter particles.