The aging effect in an ultrafine-grained Al-5% Fe alloy produced by severe plastic deformation

A new approach was employed to create a metastable supersaturated solid solution of iron in aluminum and to form a precipitation-strengthened ultrafine-grained (UFG) structure in the rapidly quenched Al-5 wt% Fe alloy using severe plastic deformation (SPD) by torsion under a high pressure. In the process of short-term heating in a temperature range of 20-450degreesC, structural changes in the samples thus deformed were studied by transmission electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry. An UFG structure that consists of a supersaturated solid solution of iron in aluminum with an average grain size of 150 nm and refined intermetallic particles was shown to form in the hypereutectic two-phase alloy due to rapid quenching and SPD. The aging regimes that bring about a maximum strength of the alloy were determined. Time and temperature dependences of the microhardness were studied. It was shown that the high-strength state in the alloy may be realized after a combined treatment including rapid quenching, SPD, and aging.