Achieving ultrahigh strength in binary Al-10Mg alloy through heavy cryogenic rolling

Al-Mg alloys with high Mg contents have attracted considerable interest given enhanced strength and si-multaneously reduced density by high Mg solute concentrations. In the present study, we proposed a strategy of strengthening Al-10wt%Mg binary alloy via heavy cryogenic rolling at liquid nitrogen tem-perature. Both cryogenic plastic deformation and a high concentration of Mg solute effectively suppress dynamic recovery during rolling, creating nanoscale and ultra-fine laminated grains containing a high density of dislocations in a nearly single-phase solid solution. The as-rolled Al-10wt%Mg exhibits an average 0.2% offset tensile yield strength of 619 MPa, and average engineering and true ultimate tensile strengths of 689 and 726 MPa, accompanied by average uniform elongation of 5.3% exceeding the threshold value of 5% required for structural engineering applications. The high strength stems from enhanced solid-solution strengthening of a high concentration of Mg solute, significant grain boundary strengthening of nanoscale and ultra-fine laminated grains, and strong dislocation strengthening. The appreciable ductility can be primarily attributed to a high concentration of Mg solute that can retard dynamic recovery processes during tensile testing by impeding dislocation motion, thus enhancing dislocation accumulation and work -hard-ening ability. A high concentration of Mg solute combined with cryogenic plastic deformation to a high strain magnitude provides a new avenue to achieve ultrahigh strength and good ductility in non-age -hardened Al-Mg alloys. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a strategy of strengthening Al-10wt%Mg binary alloy via heavy cryogenic rolling at liquid nitrogen temperature was proposed. The combination of cryogenic plastic deformation and a high concentration of Mg solute effectively enhanced the strength and ductility of the alloy, providing a new avenue for non-age-hardened Al-Mg alloys to achieve ultrahigh strength and good ductility.