Strength properties and structure of a submicrocrystalline Al–Mg–Mn alloy under shock compression

Abstract

The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg–0.6Mn–0.11Si–0.23Fe–0.03Cr–0.02Cu–0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 10⁴ s^–1. The average size of crystallites in the alloy was 180–460 nm. Hugoniot elastic limit σ_HEL, dynamic yield stress σ_y, and the spall strength σ_SP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σ_HEL and σ_y of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σ_sp does not depend on the grain size. The maximum value of σ_HEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σ_y = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σ_sp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased.