Influence of the microstructure on the physicomechanical properties of the aluminum alloy Al–Mg–Si nanostructured under severe plastic deformation

The microstructural features, strength, and electrical conductivity of the electrotechnical aluminum alloy 6201 of the Al–Mg–Si system was investigated. The alloy was nanostructured using severe plastic deformation by high pressure torsion at different temperatures and in different deformation regimes. As a result, the samples had an ultrafine-grain structure with nanoinclusions of secondary phases, which provided an excellent combination of high strength (conventional yield strength $\sigma_{0.2}$ = 325–410 MPa) and electrical conductivity (55–52% IACS). The contributions from different mechanisms to the strengthening were analyzed. It was experimentally found that the introduction of an additional dislocation density (an increase from 2 $\cdot$ 10$^{13}$ до 5 $\cdot$ 10$^{13}$ m$^{-2}$) with the same basic parameters of the ultrafine-grain structure (grain size, size and distribution of particles of secondary strengthening phases) leads to an increase in the strength of the alloy by $\sim$ 15%, while the electrical conductivity of the material changes insignificantly. The contribution from grain boundaries to the electrical resistivity of the alloy with an ultrafine-grain structure upon the change in their state, most likely, due to a change in the degree of nonequilibrium was estimated.