Improved Ductility by Reducing Powder Size in Laser Powder Bed Fusion of AlSi10Mg

Strict control of powder properties, especially particle size distribution (PSD), is critical in the laser powder bed fusion (LPBF) process to ensure the quality of the fabricated parts. This work shows that reducing the powder size could improve the ductility of LPBF fabricated AlSi10Mg. The tensile elongation increased from 4.1% to 8.8% when AlSi10Mg powder sizes (D50 value) decreased from 76 µm to 16 µm in the as-fabricated state. Our results showed that fine powder size stimulates epitaxial grain growth due to excessive remelting. The presence of epitaxial columnar grains makes the crack path across inner melt pools more frequent and travels from the coarse melt pool zones to the fine melt pool zones. This work suggests that powder size is a crucial factor to be considered in maintaining repeatable mechanical properties in LPBF processes, particularly when ductility and ductility-dominated properties are critical.