The evolutions of mechanical properties and microstructures of Al-Mg-Mn-Sc-Zr alloy during dynamic stretching deformation

Abstract Metal materials usually show better mechanical properties during dynamic deformation. Al-Mg-Mn-Sc-Zr alloy is taken as the object in this research and the dynamic stretching behaviors are studied at a wide range of strain rate (0.001 s−1–800 s−1). This research finds that the peak stress and elongation of Al-Mg-Mn-Sc-Zr alloy exhibit significant increasing tends as the strain rates increase. The alloy’s work hardening ability is also improved. During dynamic stretching processes, the deformation time is short and there is not enough time for dislocations to undergo annihilation and rearrangement processes. The dynamic recovery process is severely inhibited, which not only retains the higher density of dislocations, but also improves the uniformity of dislocation distributions. As the strain rate increases, the movement velocity of the dislocations also increase, resulting in a decrease in the width of the dislocations. The increase on the dislocation density and the decrease on the width of the dislocations increase the resistance to the movement of the dislocations. As a result, the peak strength enhances significantly. Dislocation with high movement velocity can cut through Al3(Sc,Zr) particles when the strain rate exceed 500 s−1. Consequently, the formation of dislocation tangles is inhibited, leading to the reduction of flow localization areas and improvement of the uniformity of dislocation distributions. The improvement of dislocation distribution uniformity improves the plasticity of the alloy during dynamic deformation significantly.