Influence of severe plastic deformation on dynamic strain aging of ultrafine grained Al-Mg alloys

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The purpose of the proposed project are 1) to explore the influence of SPD processing on DSA and the PLC effect of UFG Al-Mg alloys and 2) to explore the influence of DSA and the PLC effect on the deformation behavior of SDP-processed UFG Al-Mg alloys. Investigations carried out during the first period revealed a strong influence of both extrinsic SPD processing on DSA and intrinsic DSA effect on the deformation behavior of as-SPDed UFG Al-Mg alloys at room temperature (see the work report and the project-related publication [1] for the first period listed in the section 1 of this application). In order to gain a deeper physical insight into these complex mutual interactions, performed theoretical analysis based on the experimental results must be conducted in the second period. For this purpose, recently developed models for DSA in coarse grained/small strained FCC alloys and strain hardening at very large strains of FCC metals and alloys will be utilized. However, they have to be modified to account for the drastically refined grain size, the severely increased dislocation density and consequently, an enhanced solute diffusivity in the as-SPDed Al-Mg alloys. The microstructural, mechanical and thermodynamic data which are necessary for the model modifications will be taken from the experimental results. Therefore, in the second period the experimental investigations will be extended from RT to elevated temperatures (at 50 °C, 100 °C, 200°C and 300 °C, respectively). The information of microstructural evolution and mechanical behavior of as-SPDed UFG Al-Mg alloys at elevated temperatures, as well as thermodynamic parameters that control the DSA intensity and kinetics, like solute diffusivity, deformation activation energy/binding energy between solute atoms and arrested mobile dislocations, will be obtained by the intelligent microstructural and mechanical experimental investigations. The respective domain that limits the range of DSA/PLC effect in the UFG Al-Mg alloys (e.g. Al-1Mg and Al-5Mg) at the temperatures from RT to 300 °C and at the strain rates from 10-5s-1 to 10-3s-1 will be built on the basis of the theoretical model predictions and experimental results.