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 x 10(13) to 5 x 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 similar to 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.