Characteristic microstructure and microstructure evolution in Al–Cu–Mn alloy under projectile impact

The microstructure and microstructural evolution were investigated near crater wall in Al–Cu–Mn alloy using optical and transmission electron microscopy (TEM) after projectile impaction. The results show that three characteristic zones around the crater can be classified based on the different microstructure, i.e. deformation bands, dynamic recovery zone and adiabatic shear bands (ASBs). The TEM observation indicates that the dislocation glide plays a crucial role in the formation of that microstructure during projectile impact. The adiabatic shear bands were formed near the crater wall and extend into matrix. It can be found that fine grains were formed within the adiabatic shear bands by dynamic recrystallization occurring during projectile impact. The micro-cracks have been developed along the adiabatic shear bands. However, It is demonstrated that the formation of deformation bands are favorable for improving anti-impact property of Al–Cu–Mn alloy, but adiabatic shear bands are easily to initiate micro-cracks, leads to the failure of target material.