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

Abstract

The high strength and lightweight benefits of Al-Cu-Li alloys make them attractive for aerospace applications. The major strength contributing phase is the T₁(Al₂CuLi) phase. Although extensive reporting is known on its nucleation behaviour and structure in conventional T₁ microstructures, little is known for additive manufacturing (AM). This work focusses on the comparative characterisation of T₁ 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 T₁ microstructures are achievable.