Stabilizing a severely deformed Al–7Mg alloy with a multimodal grain structure via Mg solute segregation

•Enhanced thermal stability at ≤ 275 ℃ was obtained in an ECAP-processed binary Al–7Mg alloy.•It owes to the multimodal structure in the as-ECAPed sample, with nano-, ultrafine- and micron-sized grains.•Strong segregation and/or clusters of Mg solute along GBs obtained during ECAP also contribute to it.•Nanoscale Al3Mg2 precipitates formed during annealing can inhibit grain growth by pinning GBs.