a b s t r a c tThe effects of cold deformation prior to aging on the precipitation behavior, microstructure and mechanical properties of an Al-5.6Cu-0.72 Mg-0.5Ag-0.32Mn-0.17Sc-0.12Zr (in wt%) alloy were investigated. Pre-straining disrupts the formation of Mg-Ag co-clusters, modifying the normal precipitation sequence. A strong increase in the dislocation density by a factor of 100 leads to a $ 40% decrease in the number density, N V , of the Ω-phase at pre-strains of εZ1% (εZ 0.01). The aspect ratios of the platelets in this phase increased from $ 21 to $ 42 after a negligible pre-strain of r1% (ε r0.01) and further decreased to $ 25 in the pre-strain interval of 1-80% (ε $ 0.01-1.61). In addition, the nucleation of the Cu-rich θ 0 -phase occurs on dislocations. The heterogeneous nucleation of the thick Ω-phase particles with low aspect ratios ( $ 12) and equiaxed particles of S-phase with dimensions r5 nm on the deformation-induced boundaries was found. After peak aging, the yield stress (YS) and ultimate tensile strength (UTS) increased from 4787 4 MPa and 522 78 MPa for the as-quenched alloy to 516 7 4 MPa and 568 7 6 MPa in the longitudinal and 5547 5 MPa and 601 73 MPa in the transversal directions, respectively, for the alloy subjected to pre-straining with a rolling reduction of 80% (ε $ 1.61). Cold rolling prior to aging induces the anisotropy in mechanical behavior through the formation of deformation bands.

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wt. %) alloy was examined in detail after aging at 170°C with different dwell times up to 96 h. Deformation by 3%stretching prior to aging was used to investigate the effect of dislocations on phase and hardness evolution and compared with the undeformed material. The small pre-deformation led to a slight decrease of peak strength due to reduced homogenous nucleation. Strong interaction between different phases caused the formation of hybrid structures both in the undeformed bulk areas and on dislocations. These phases consist of different fragments of the GP zones, θ"and θ'-phases from the Al-Cu system, GPB zones and S1-phase from the Al-Cu-Mg system, and β"-, β'-Cu, C-and Q'-phases from the Al-Mg-Si-Cu system. A new phase named C1, isostructural to the C-phase but having a different orientation with the Al matrix -(010) C //(010) Al , [001] C //[101] Al , has been found predominantly on dislocation lines, and to a lesser extent in hybrid precipitates in the bulk. Calculations of structural stability by density functional theory (DFT) were performed on experimentally found structures, consisting of a C-phase core in two different orientations, and having Cu segregations in GP-like structures at their interfaces with the matrix.

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