Unveiling the deformation mechanism of extruded 7003 aluminum alloy matrix under high-speed impact affected by adiabatic shear

The effect of adiabatic shear on the deformation mechanism of extruded 7003 aluminum alloy matrixes during high-speed impact is investigated using a split Hopkinson pressure bar. The results reveal significant differences in the deformation behavior of the matrix on both sides of adiabatic shear band (ASB), which is strongly influenced by adiabatic shear behavior. In Region A, the grains undergo significant bending deformation, and as the strain increases, new ASBs are formed in this region. In contrast, in Region B, some grains retain their initial fibrous morphology during high-speed impact. The microstructure evolution within the fibrous grains in Region B proceeds as follows: dislocation proliferation, dislocation entanglement to form dislocation walls, dislocation cellulation, and further evolution into subgrains. Visibly, the plastic deformation of the matrix is mainly borne by Region A, which gradually transforms to Region B as strain increases. Relatively, the deformation in Region A is more pronounced, exhibiting clear strain hardening (SH) until 0.60 strain. As strain increases to about 0.81, softening due to temperature rise becomes the dominant deformation mechanism. In contrast, Region B exhibits continuous softening during the entire deformation period. Overall, the plastic deformation of the 7003 alloy exhibits softening behavior after peak stress, which can be roughly divided into six stages. The primary deformation mechanisms in each stage are as follows: softening of the entire matrix, localized SH within ASB, localized softening within ASB, localized SH in Region A, localized softening in Region A, and SH and softening in Region B.