The microstructure evolution of X2A66 aluminum-lithium alloy during hot deformation was analyzed. When the deformation temperature was 420°C and the strain rate was 0.01 s–1

sub-grain structure was incomplete in the matrix and a small amount of dynamic recrystallized grains were observed. When the deformation amount reached 80%

a flat and clear grain boundary and low dislocation density in the matrix can be observed. When the amount of deformation was greater than 80%

a large number of dislocations occurred in a part of the grain and impeded dislocation motion around the precipitated phase. T1 phase appeared to be broken and remelted and the δ′ phase was precipitated during high temperature deformation. The crushing and remelting of the T1 phase caused the matrix to re-saturate

especially the supersaturation of the Li element

which promoted the precipitation of the δ′ phase. The precipitation phase inside the grain boundary can effectively hinder the dislocation movement and increase the nucleation rate of recrystallized grains. The precipitated phase pinned on the grain boundary reduced the dynamic recrystallization rate by hindering the movement of the grain boundary and the sub-grain boundary