<b>Precipitation evolution, aging strengthening and thermal stability in Al‑Fe‑Mg‑Zr eutectic alloy via laser powder bed fusion</b>

Conventional precipitation-hardened aluminum alloys experience severe mechanical degradation above 200 °C due to precipitate coarsening and dissolution. This study presents a novel Al-Fe-Mg-Zr eutectic alloy fabricated via laser powder bed fusion, achieving ultrafine grains and heterostructure (cell and lamella). Direct aging (400 °C/4 h) enhances yield strength to 376.1 MPa (72.6% increase) and ultimate tensile strength to 405.8 MPa (30.7% increase) compared to the as-printed condition, while reducing ductility to 11.1%. The strengthening mechanisms arise from grain boundary strengthening, precipitation strengthening via coherent L1₂-Al₃Zr nanoscale dispersoids, dislocation strengthening, and effective load transfer through submicron-scale Al-Fe intermetallic phases. After prolonged thermal exposure (400 °C/100 h), the alloy retains good mechanical properties, demonstrating excellent heat resistance due to the low coarsening rate of Al₁₃Fe₄ (0.96 nm³/s) and sustained Al₃Zr precipitates. The dual-scale strengthening strategy significantly advances developing high-strength and thermally stable Al alloys for high-performance applications.