Microstructure evolution and mechanical properties of 2195 Al-Li alloy with different heat-treatment states via friction stir additive manufacturing

• FSAM effectively refines grains and increases high-angle grain boundaries in 2195 Al-Li alloys, regardless of initial heat-treatment state (T3 or T8). • The heat-treatment state has minimal influence on the final microstructure after FSAM, as processing temperatures exceed the solid solution temperature. • Tensile strengths of the nugget zone reach up to 478 MPa (T3) and 481 MPa (T8) in lap experiments, demonstrating significant mechanical property improvements. • The study provides a foundation for optimizing FSAM parameters to achieve tailored microstructures and enhanced performance in aerospace-grade Al-Li alloys.