Characterisation of T₁ (Al₂CuLi) Precipitates in Conventional (2099-T83) and Laser Additive Manufactured (PBF-LB/M, DED-LB/M) Microstructures

The high strength and lightweight benefits of Al-Cu-Li alloys make them attractive for aerospace applications. The major strength contributing phase is the T 1 (Al 2 CuLi) phase. Although extensive reporting is known on its nucleation behaviour and structure in conventional T 1 microstructures, little is known for additive manufacturing (AM). This work focusses on the comparative characterisation of T 1 phase (structure, nucleation behaviour) in conventional (2099-T83), Powder Bed Fusion (PBF-LB/M) and Direct Energy Deposition (DED-LB/M) AA2099 microstructures. It is shown that with different AM processes and heat treatments, different T 1 microstructures are achievable.