Influence of alloying elements on laser powder bed fusion processability of aluminum: A new insight into the oxidation tendency

This study focuses on the influence of alloying elements (Si and Mg) and the process parameters on the laser powder bed fusion (LPBF) processability of aluminum (Al). In this regard, pure Al, AlSi12, and AlSi10Mg parts with and without single tracks on their top surface were fabricated using a wide range of process parameters. The oxidation tendency, laser absorptivity, and powder attributes were evaluated to justify the densification level and the processing window of the fabricated parts. The starting powders were subjected to the Auger electron spectroscopy to characterize the nature of the oxide compounds participating in the melt pool. The measurement of the oxygen content in pure Al (2260 ppm), AlSi12 (1299 ppm), and AlSi10Mg (740 ppm) powders, as well as their printed parts (90, 220, and 130 ppm, respectively at laser power of 300 W), proved that the level of oxide removal overweighs any possible in-situ oxidation of the molten Al/Al alloys. A mechanism was proposed to explain the release of oxygen, confirmed by microstructural observations and oxygen elemental map analysis. This study indicates that neither the laser absorptivity of AlSi12 (58.4%) and AlSi10Mg (56.1%) alloys nor the high oxidation affinity of pure Al adversely affects their processability.