• Direct aging (DA) significantly enhances the strength of LPBF TiB2/AlSi7Mg alloys while preserving ductility, with optimal under-aging at 150°C for 4 h yielding YS of 361 MPa, UTS of 503 MPa, and elongation of 9.1%.
• DA promotes the formation of nanoprecipitates (Si and β'-Mg1.8Si phases) within the α-Al matrix without altering the grain size or cellular structure, contributing to strengthening via Hall–Petch and Orowan mechanisms.
• Under-aging (UA) results in a balanced work-hardening response, whereas over-aging (OA) leads to rapid saturation of work hardening due to dynamic recovery, limiting uniform elongation.
• The study validates DA as an effective post-processing strategy for enhancing the mechanical performance of LPBF Al–Si–Mg alloys for engineering applications, particularly in aerospace and transportation.