Solid-state alloying of Al-Mg alloys by accumulative roll-bonding: Microstructure and properties

In this study, a novel solid-state alloying approach was adopted to fabricate Al-Mg alloys with high Mg contents (CMg) by accumulative roll-bonding (ARB) of Al and Mg elemental materials to ultrahigh cycles. Experimental results showed that the degree of alloying increased with the increase of ARB cycles and a supersaturated α-Al solid solution accompanied with nanoprecipitates was formed in the Al-Mg alloys by ARB to 70 cycles. The as-prepared Al-Mg alloys exhibited enhanced mechanical properties, with a maximum tensile strength of ∼ 615 MPa and a tensile elongation of ∼ 10% at CMg = 13 wt.%. The high strength can be attributed to different mechanisms, namely solid solution strengthening, grain boundary strengthening, dislocation strengthening, and precipitation strengthening. The Al-Mg alloys showed increased work hardening with increasing CMg, due to the enhanced formation of nanoprecipitates. Meanwhile, no obvious drop in the intergranular corrosion (IGC) resistance was found in the Al-Mg alloys with CMg up to 13 wt.%. Moreover, sensitization treatment was found to induce little decrease in the IGC resistance of the Al-Mg alloys with CMg ≤13 wt.%. We found that the excellent IGC resistance was due to the suppression of grain boundary precipitation by the preferred formation of precipitates within the grains that were induced by ARB. Our study indicated the novelty of the present solid-state alloying approach to achieving a superior combination of high mechanical properties and IGC resistance in Al-Mg alloys.