Microstructural evolution of 2099 AlLi alloy during friction stir welding process

Microstructural evolution of friction stir welded 2099 AlLi alloy was evaluated. Friction stir welding (FSW) resulted in significant grain refinement, dissolution of original phases T1 (Al2CuLi) and δ′ (Al3Li), and precipitation of ultrafine δ′ phases in the nugget zone (NZ). In the heat affected zone (HAZ), heavy precipitation of T1 phases led to a peak hardness of 105 HV. A strong rotated Cube texture {013} 〈100〉 was obtained in the base metal (BM). After FSW the NZ was characterized by shear texture {111} 〈110〉, while Bass texture {110} 〈112〉 and S texture {123} 〈634〉 were developed in the thermo-mechanically affected zone (TMAZ). Compared with the BM, the dislocation density was decreased in the welding zones, which resulted from recovery and recrystallization.