Enhanced strength and electrical conductivity of ultrafine-grained Al-Mg-Si alloy processed by hydrostatic extrusion

The effect of hydrostatic extrusion combined with an artificial aging on microstructure, mechanical and electrical properties of 6101 Al-Mg-Si alloy was investigated. It has been shown that such thermo-mechanical treatment is an effective method for producing of long wires with an ultrafine-grained microstructure (grain size of 300–400nm) and enhanced ultimate tensile strength (>330MPa) and electrical conductivity (up to 58% IACS). The mechanical behavior of 6101 Al-Mg-Si alloy depended strongly on applied strains by hydrostatic extrusion and crystallographic texture. Higher accumulative strain accelerated the precipitation kinetics but decreased the age hardening response. The double fiber ⟨100⟩ and ⟨111⟩ texture was observed for hydrostatically extruded samples. The ⟨001⟩ grains with homogenously distributed needle-like β″ precipitates provided precipitation strengthening of material while ⟨111⟩ grains resulted in more efficient grain boundary strengthening. Quantitative microstructure characterization allowed adjusting physical model to estimate the electrical conductivity and compare it with experimental data. The high conductivity was provided mainly by decomposition of solid solution due to precipitation of needle-like β″ precipitates in the grain interior and spherical β′ or β particles located at grain boundaries. •Al-Mg-Si alloy was subjected to hydrostatic extrusion combined with aging treatment.•UFG Al-Mg-Si alloy with UTS of 332MPa and conductivity of 58% IACS was obtained.•Precipitation process depended on applied strains and crystallographic texture.•Strengthening effect was achieved by UFG structure and needle-like β″ precipitates.•Precipitation of β″ and spherical β′/β particles at GB provided high conductivity.