Microstructure evolution of 2195 Al-Li alloy subjected to high-strain-rate deformation

2195 Al-Li alloy is firstly processed by means of split Hopkinson pressure bar (SHPB). Two means of loading methods are conducted at room temperature, namely uni-axial impact and multi-directional impact. The nominal strain rates reach up to 1.2×10³s^-1 and 2.8×10³s^-1 respectively, with the total strain 1.6 and 3.6. TEM microstructure observations reveal that initial coarse grains are refined significantly. The grains of uni-axial impacted sample are elongated, whose width/length average grain sizes are 178nm and 311nm. In contrast, the grains of multi-directional impacted sample are equiaxed with an average grain size of 362nm. Dynamic recovery is suppressed during dynamic plastic deformation (DPD), dislocations could not reach equilibrium states. High densities of dislocations are generated, forming several kinds of configurations. Interactions of dislocation substructures and fragment of grains result in the refinement of grains.