Direct aging of AlSi10Mg alloy produced by powder bed fusion – laser beam: Eliminating the need for solution heat treatment

The AlSi10Mg alloy is widely used in metal additive manufacturing (AM), yet optimal post-processing routes for components produced by Powder Bed Fusion-Laser Beam (PBF-LB/M) remain unclear due to their highly refined and non-equilibrium microstructures. Conventional T6 heat treatments, effective for cast alloys, often cause softening in PBF-LB/M AlSi10Mg. This work establishes aging curves through a systematic assessment of temperature-time combinations and correlates them with microstructural evolution and mechanical behavior. The as-built alloy exhibited a supersaturated and highly refined non-equilibrium microstructure, resulting in high tensile strength. Among all evaluated conditions, direct aging at 150°C for 2 h (DA 150/2.0) produced the highest hardness and tensile performance without prior solution treatment. Natural aging for at least 48h was required to achieve peak hardness. DA 150/2.0 preserved the eutectic Si network while promoting dense precipitation of nanometric Si particles, which improved strengthening via the Orowan mechanism. This condition increased yield and ultimate tensile strengths by 17% and 13%, respectively, and enhanced ductility relative to the as-built state. Higher-temperature treatments dissolved the cellular structure and coarsened Si, reducing strength. Overall, this study demonstrates that low-temperature direct aging offers an efficient route to optimize the strength-ductility balance of PBF-LB/M AlSi10Mg without solution treatment.