On the evolution of heterogeneous microstructure and microtexture in impacted aluminum–lithium alloy

• Extensive shear banding in high strain rate deformed AA 2099-T8 alloy.
• Sub-micron grains and small spherical second phase particles in shear band.
• Large elongated grains with plate like particles in other region.
• Evidence of continuous and geometric dynamic recrystallization.

The microstructure and texture evolution in an aluminum–lithium alloy showing adiabatic shear band after dynamic deformation has been carried out using electron backscatter diffraction and bulk texture measurement using X-ray diffraction. The uniquely heterogeneous microstructure is characterized by fine sub-micron grains of the matrix phase and small spherical precipitates while the region away from the shear band shows deformed elongated grains and plate shaped precipitates. The interface between the shear band and rest of the sample shows unique deformation features indicating the existence of both continuous as well as geometric dynamic recrystallization in the impacted sample. It is inferred that the coarse grain size accompanied with heterogeneous deformation conditions during dynamic loading leads to the coexistence of competing recrystallization mechanisms in aluminum–lithium alloy.