Process-specific design strategy enables exceptional as-deposited strength-ductility synergy in novel Al-Ce alloys via additive friction stir deposition (AFSD)

A process-specific alloy design strategy was employed to achieve exceptional as-deposited strength-ductility synergy in Al-Ce alloys, eliminating the need for post-aging treatments. Al-Ce alloys, known for their excellent creep resistance and thermal stability due to the Al11Ce3 phase, were optimized using CALPHAD simulations to incorporate solid solution and precipitation strengthening in addition to composite strengthening from the Al11Ce3 phase. Additive friction stir deposition (AFSD) was used to fabricate 3D builds from cast material, refining the grain size and microstructure by fragmenting Al11Ce3 lamellae into smaller, uniformly dispersed particles and inducing Al3Sc nanoprecipitates during deposition. Microstructural and mechanical analyses revealed remarkable improvements: while the cast alloy fractured at 230 MPa with no ductility, the AFSD alloy achieved a yield strength of 385 MPa, UTS of 530 MPa, and 12.6% plastic strain. These as-deposited properties surpassed those of cast, extruded, HIPPed, or LPBF/DED Al-Ce alloys, including the previous results obtained after aging. This strategy leverages AFSD-specific process dynamics, such as intense deformation and localized high temperatures, to enable in-situ precipitation and microstructural refinement with exceptional mechanical properties, offering a transformative pathway for designing energy-efficient, high-performance materials.