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Methods of optical metallography, X ray diffraction, and transmission and scanning electron microscopy were used to study changes in the structure of the aluminum alloy D16 (2024) caused by isother mal rolling at a temperature of liquid nitrogen. It has been established that the basic structural changes that take place in the material upon deformations to e ~ 2.0 are due to the formation and evolution of the dislo cation structure, which contains cells of nanometer size. With further straining to e~3.5, the processes of recovery and recrystallization become activated, which lead to the formation of a mixed grain-subgrain nanosized structure.

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The effects of severe plastic deformation (SPD) by isothermal rolling at the temperature of liquid nitrogen combined with prior- and post-SPD heat treatment, on microstructure and hardness of Al-4.4%Cu-1.4%Mg-0.7%Mn (D16) alloy were investigated. It was found no nanostructuring even after straining to 75%. Сryodeformation leads to microshear banding and processing the high-density dislocation substructures with a cell size of ~ 100-200 nm. Such a structure remains almost stable under 1 hr annealing up to 200oC and with further temperature increase initially transforms to bimodal with a small fraction of nanograins and then to uniform coarse grained one. It is found the change in the alloy post–SPD aging response leading to more active decomposition of the preliminary supersaturated aluminum solid solution, and to the alloy extra hardening under aging with shorter times and at lower temperatures compared to T6 temper.

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Effects of severe plastic deformation by isothermal сryorolling at a temperature of liquid nitrogen with a strain of e ~ 2 and subsequent aging on structure, hardness and resistance to intergranular corrosion (IGC) of the preliminary quenched ingots of the conventional and Zr modified composition of D16 aluminum alloy, were investigated. It was found that both the alloys in the natural aged condition demonstrate slight effect on IGC resistance. It was caused by low difference in electrochemical potentials between the matrix and Guinier-Preston-Bagaratsky zones. Artificial aging at 190°C for 12 hrs to the maximum strength (T1 route) led to strong decrease in IGC resistance of both rolled and non-rolled states of the alloys due to precipitation of strengthening phases. Modification the D16 alloy composition via substitution of Mn by twice less amounts of Zr and decrease in impurity contents had a minor influence on its structure and hardness in the initial and rolled conditions. However, it significantly enhanced corrosion resistance, reducing its depth and intensity, in both naturally and artificially aged conditions. It was concluded that the main factors, determining the alloy microstructure changes, mechanical and corrosion behavior, are the volume fraction, morphology, and spatial distribution of second phases -excess phases and precipitates.