Aluminum alloys utilized in laser powder bed fusion (LPBF) processes are primarily based on the Al-Si system due to the high susceptibility of Al alloys to cracking under the rapid cooling rates characteristic of LPBF. Silicon is incorporated to modulate melt viscosity and mitigate crack formation. Among these alloys, AlSi10Mg is the most commonly used in LPBF. Current research focuses on enhancing the mechanical properties of these alloys by incorporating rare earth elements, such as scandium and zirconium, albeit with increased costs.

This study investigates a novel aluminum alloy, AlSi3.5Mg2.5 (commercially known as Custalloy), characterized by a Mg-Si content exceeding 1.85 wt.% Mg₂Si. The alloy specimens were fabricated using a DMG MORI LASERTEC 30 SLM system at varying build plate temperatures to explore the effects of in-situ aging. Test samples were produced for parameter optimization and analyzed for porosity using optical microscopy. Additionally, the microstructure of the samples was examined in both the as-built (AB) and direct-aged (DA) conditions using optical microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The alloy is analyzed by the means of CALPHAD method.

Keywords: selective laser melting; laser powder bed fusion; aluminum; aging behaviour; Custalloy