Abstract
The aim of this work was to investigate the dependence of the microstructure and mechanical properties of 7475 aluminium alloy on the processing route via severe plastic deformation (SPD). To this end two SPD techniques were used: hydrostatic extrusion (HE) and high-pressure torsion (HPT). They were carried out at room temperature to approximately the same accumulated true strain. Prior processing, the samples were subjected to two different treatments: (i) solution annealing followed by water quenching and (ii) solution annealing, quenching and ageing. It was found that, although in general, SPD leads to a similar significant increase of mechanical strength, the properties depend on the initial microstructure and processing route. In the case of HE, the samples deformed immediately after quenching exhibit higher mechanical strength whereas for HPT, aged samples possess higher strength. The results are discussed in terms of the influence of processing parameters and initial microstructure on microstructure evolution of 7475 aluminium alloy.

Key words
aluminium alloys, severe plastic deformation (SPD), hydrostatic extrusion (HE), high-pressure torsion (HPT), microstructure, mechanical properties

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