A custom Al alloy, Al92Ti2Fe2Co2Ni2, was fabricated using selective laser melting (SLM) to achieve ultrastrong and deformable properties. The alloy features heterogeneous nanoscale intermetallic lamellae, resulting in high strength (>700 MPa) and significant plastic deformation. Microstructural analysis revealed a combination of Al-rich matrix, nanoscale intermetallics, and fine rosettes, contributing to the alloy's mechanical properties. Micropillar compression tests showed high flow stress (up to 900 MPa) and significant back stress, indicating effective deformation mechanisms. Post-deformation analyses revealed complex dislocation structures and stacking faults in the brittle intermetallic phase, Al9(Fe,Co,Ni)2. The study demonstrates that introducing heterogeneous microstructures and nanoscale intermetallics can enhance the strength and deformation capability of additively manufactured Al alloys. The alloy's high strength and plasticity are attributed to the large back stress from heterogeneous intermetallic nanolaminate interfaces. The medium entropy monoclinic Al9(Fe,Co,Ni)2 intermetallic phase also exhibited significant plasticity, suggesting unique deformation mechanisms. The results highlight the potential of nanoscale intermetallic rosettes in designing ultra-strong, deformable Al alloys. The alloy's mechanical properties were evaluated through nanoindentation, bulk compression, and micropillar compression tests, revealing high engineering stress and plastic strain. The study provides insights into the deformation mechanisms and strengthening effects of intermetallics in additively manufactured Al alloys.A custom Al alloy, Al92Ti2Fe2Co2Ni2, was fabricated using selective laser melting (SLM) to achieve ultrastrong and deformable properties. The alloy features heterogeneous nanoscale intermetallic lamellae, resulting in high strength (>700 MPa) and significant plastic deformation. Microstructural analysis revealed a combination of Al-rich matrix, nanoscale intermetallics, and fine rosettes, contributing to the alloy's mechanical properties. Micropillar compression tests showed high flow stress (up to 900 MPa) and significant back stress, indicating effective deformation mechanisms. Post-deformation analyses revealed complex dislocation structures and stacking faults in the brittle intermetallic phase, Al9(Fe,Co,Ni)2. The study demonstrates that introducing heterogeneous microstructures and nanoscale intermetallics can enhance the strength and deformation capability of additively manufactured Al alloys. The alloy's high strength and plasticity are attributed to the large back stress from heterogeneous intermetallic nanolaminate interfaces. The medium entropy monoclinic Al9(Fe,Co,Ni)2 intermetallic phase also exhibited significant plasticity, suggesting unique deformation mechanisms. The results highlight the potential of nanoscale intermetallic rosettes in designing ultra-strong, deformable Al alloys. The alloy's mechanical properties were evaluated through nanoindentation, bulk compression, and micropillar compression tests, revealing high engineering stress and plastic strain. The study provides insights into the deformation mechanisms and strengthening effects of intermetallics in additively manufactured Al alloys.